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Full text of "The physiology of man; designed to represent the existing state of physiological science as applied to the functions of the human body"

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MEDICAL 




Jodloal Library Bxohsngf 



WORKS BY THE SAME AUTHOR: 
Published ty D. Appleton & Company. 



The Physiology Of Man ; designed to represent the Existing State 

of Physiological Science as applied to the Functions of the Human 

Body. Volume I., Introduction; Blood; Circulation; Kespiration. 

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Chyle. 1 vol., 8vo, cloth, pp.550. Price $4.50. 
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Animal Heat; Movements; Voice and Speech. 1 vol., 8vo, cloth. 

pp.520. Price $4.50. 
The same, Vol. IV., The Nervous System. 1 vol., 8vo, cloth, pp. 470. 

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Recherches experimentales sur une nouvelle fonction du 
foie, consistant dans la separation de la cholesterine du sang et son 
61imination sous forme de stercorine (seroline de Boudet), Paris, 
Germer Bailiere; and New York, D. Appleton & Company, 1868. 
1 vol., 8vo. pp. 122. Price $0.75. 

This work received an "Honorable Mention" with a "Recom- 
pense" of 1,500 francs from the Institute of France (Academie des 
Sciences), in 1869, Concours Montyon (Medecine et Ckirurgei). 

On the Physiological Effects of Severe and Protracted Mus- 
cular Exercise ; with special Eeference to its Influence upon the 
Excretion of Nitrogen. 1871. 1 vol., Svo, cloth, pp.91. Price $2.00. 

Manual of Chemical Examination of the Urine in Disease ; 

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MEDICAL 

HE LIBRARY, 



PHYSIOLOG 



tv, 



pester, 



DESIGNED TO REPRESENT 



THE EXISTING STATE OF PHYSIOLOGICAL 
SCIENCE, 



AS APPLIED 



TO THE FUNCTIONS OF THE HUMAN BODY. 



BY 

AUSTIN FLINT, JR., M.D., 

PSOFESSOB OF PHYSIOLOGY AND PHYSIOLOGICAL ANATOMY IN THE BELLEVUE HOSPITAL 

MEDICAL COLLEGE. NEW YORK; ATTENDING PHYSICIAN TO THE BELLEVUE HOSPITAL; 

CONSULTING PHYSICIAN FOB THE CLASS OF NEBVOU8 DISEASES TO THE BU- 

BEAU OF MEDICAL AND 8UEGICAL BELIEF FOB OUT-DOOB POOB, 

BELLEVCE HOSPITAL; FELLOW OF THE NEW YOBK ACADEMY 

OF MEDICINE ; MEMBEB OF THE MEDICAL SOCIETY 

OF THE COUNTY OF NEW YOBK, ETC., ETC. 



NERVOUS SYSTEM. 



NEW YOKK: 
D. APPLETON AND COMPANY, 

549 & 551 BROADWAY. 
1873. 



ENTERED, according to Act of Congress, in the year 1872, 

BY D. APPLETON & CO., 
In the Office of the Librarian of Congress, at Washington. 



PEEF ACE. 



THERE is, probably, no subject connected with human 
physiology, which has engaged the attention of experi- 
mentalists and philosophic writers so much as the ner- 
vous system, especially within the last few years. The 
author has, from the first, looked upon this division of 
the work as the most important and the most difficult of 
all, and feels that this volume will be regarded with more 
critical interest than any one of the series ; and if he has 
succeeded, even in a measure, in giving, in it, a satisfac- 
tory representation of our present positive knowledge, no 
apology is necessary for the length of time occupied in 
its preparation. For two and a half years, he has been 
almost unremittingly engaged in writing this volume, and 
has endeavored to overcome, rather than avoid, the diffi- 
culties which have presented themselves in the investiga- 
tion of important questions, which are as yet regarded by 
many as unsettled. 

A great part of the inevitable delay which has attend- 
ed the publication of this part of the work has been due 
to the difficulty in this country of consulting rare and im- 
portant memoirs. "When it is stated that every citation 



4 PREFACE. 

has been made after a careful study of the original publi- 
cation, any one acquainted with the literature of the ner- 
vous system will appreciate the amount of labor involved 
simply in bibliographical research ; but in this depart- 
ment, more than in any other, it is necessary to avoid 
taking experiments and opinions at second-hand. The 
experience of many years, as an experimental physiolo- 
gist and a practical teacher, has enabled the author to 
verify many of the important facts stated in this volume, 
and has led to some original observations, which appear 
in the body of the work. 

The present volume treats of the physiological anatomy 
and the functions of the nervous system, as they appear 
to a practical physiologist, accustomed to accept nothing 
that is not capable of positive demonstration or well-sus- 
tained inference. Adhering conscientiously to the posi- 
tive method of study, the author has endeavored to pre- 
sent an account of the nervous system, which, though it 
will undoubtedly.be extended by future investigations, is 
made up mainly of statements of facts that will probably 
not undergo serious modification, as we advance in our 
knowledge of the subject. He has considered the proper- 
ties and functions of the cerebro-spinal and sympathetic 
nervous systems, mainly from this point of view ; and has 
touched but slightly upon psychology, which has long 
been considered a science by itself. The special senses 
have been deferred, to be taken up in the fifth and last 
volume of the series. 

The physiological anatomy of the nervous system is 
regarded by the author as an indispensable preparation 
for the study of its functions. The most reliable recent 



PREFACE. 5 

works upon histology contain, of course, much that is of 
no great physiological interest or importance, and the best 
anatomical treatises do not generally give a description 
of parts with particular reference to their physiology. To 
facilitate the thorough comprehension of the subject, the 
author has carefully detailed certain anatomical points, a 
familiarity with which is necessarily involved in an accu- 
rate study of nervous physiology. 

The publishers of this series, having lately issued 
Prof. Hammond's treatise on Nervous Diseases, are de- 
sirous of presenting a complete work on the "Physiology 
and Pathology of the Nervous System." Both Prof. Ham- 
mond and the author of this volume heartily concur in 
this plan. Though the full consideration of the physiology 
of the nervous system would perhaps be out of place in 
a treatise on nervous diseases, a thorough knowledge of 
its functions is none the less important as a preparation 
for the intelligent study of its pathology. The present 
volume was written as one of the series on the " Physi- 
ology of Man," but will also be issued as the first vol- 
ume of a complete work on the Physiology and Diseases 
of the Nervous System. It is proper to state that the 
two volumes thus published were written independently 
of each other, and that Prof. Hammond is in nowise re- 
sponsible for the author's views upon physiology, nor for 
any errors or defects that may be found in his part of the 
work. The reader, however, will find few points upon 
which there is any radical or important difference of opin- 
ion ; but where these differences occur, they have been 
frankly stated, and each author is solely responsible for 
his own opinions and statements. 



6 PREFACE. 

Finally, the author presents this volume, with the 
simple statement that he has made an honest attempt 
to compass the great subject to which it is devoted, the 
magnitude and importance of which he never appreci- 
ated so fully as at the present moment. In the prepara- 
tion of this volume, it was expected to include in it the 
special senses, and chapters upon touch, smell, and sight, 
were written, so that at least one-fifth of the last volume 
of the original series is already completed. The fifth vol- 
ume is therefore so far advanced, that it is hoped that the 
entire work will be finished within a year. The last part 
will be devoted to the Special Senses and Generation. 

NEW YORK, May, 1872. 



O ON TEN TS. 



CHAPTER I. 

PHYSIOLOGICAL DIYISIONS AXD STBUCTrBE OF THE NEBVOUS SYSTEM. 

General considerations Divisions of the nervous system Physiological anatomy 
of the nervous tissue Anatomical divisions of the nervous tissue Medul- 
lated nerve-fibres Simple, or non-medullated nerve-fibres Gelatinous 
nerve-fibres (fibres of Remak) Accessory anatomical elements of the 
nerves Branching and course of the nerves Termination of the nerves 
in the muscular tissue Termination of the nerves in glands Terminations 
of the sensory nerves Corpuscles of Pacini, or of Yater Tactile corpus- 
cles Terminal bulbs Structure of the nerve-centres Nerve-cells Con- 
nection of the cells with the fibres and with each other Accessory anatom- 
ical elements of the nerve-ceutres Composition of the nervous substance- 
Regeneration of the nervous tissue Reunion of nerve-fibres, . Page 13 

CHAPTER II. 

MOTOE AND SEXSOBY XEBVES. 

Distinct seat of the motor and sensory properties of the spinal nerves Specu- 
lations of Alexander Walker Views of Sir Charles Bell regarding the func- 
tions of the anterior and posterior roots of the spinal nerves Experiments 
of Magendie on the roots of the spinal nerves Properties of the posterior 
roots of the spinal nerves Influence of the ganglia upon the nutrition of 
the posterior roots Properties of the anterior roots of the spinal nerves 
Recurrent sensibility Mode of action of the motor nerves Associated 
movements Mode of action of the sensory nerves Sensation in amputated 
members, 66 



O CONTENTS. 

CHAPTER III. 

GENEBAL PEOPEETIE8 OF THE NEEVE8. 

Nervous irritability Different means employed for exciting the nerves Disap- 
pearance of the irritability of the motor and sensory nerves after exsection 
Nerve-force Non-identity of nerve-force with electricity Rapidity of 
nervous conduction Estimation of the duration of acts involving the nerve- 
centres Action of electricity upon the nerves Contrasted action of the 
direct and the inverse current on closing and opening the circuit Voltaic 
alternations Induced muscular contraction Galvanic current from the 
exterior to the cut surface of a nerve Effects' of a constant galvanic cur- 
rent upon the nervous irritability Electrotonus, anelectrotonus, and cathe- 
lectrotonus Neutral point Negative variation, .... Page 91 



CHAPTER IV. 

SPINAL NEEVES MOTOB NEBVES OF THE EYEBALL. 

Special nerves coming from the spinal cord Cranial nerves Anatomical classi- 
fication Physiological classification Motor oculi communis (third nerve) 
Physiological anatomy Properties and functions Influence upon cer- 
tain muscles of the eyeball Action of the inferior oblique muscle Influ- 
ence upon the movements of the iris Patheticus, or trochlearis (fourth 
nerve) Physiological anatomy Properties and functions Action of the 
superior oblique muscle Motor oculi externus, or abducens (sixth nenre) 
Physiological anatomy Properties and functions, . . .122 



CHAPTER V. 

MOTOB NEBVES OF THE FACE. 

Nerve of mastication (the small, or motor root of the fifth) Physiological anat- 
omy Deep origin Distribution Properties and functions of the nerve 
of mastication Facial nerve, or nerve of expression (the portio dura of the 
seventh) Physiological anatomy Intermediary nerve of Wrisberg De- 
cussation of the fibres of origin of the facial Alternate paralysis Course 
and distribution of the facial Anastomoses with sensitive nerves Summary 
of the anastomoses and distribution of the facial Properties and functions 
of the facial Functions of the branches of the facial within the aqueduct 
of Fallopius Functions of the chorda tympani Influence of various 
branches of the facial upon the movements of the palate and uvula Func- 
tions of the external branches of the facial, 139 



CONTENTS. 9 

CHAPTER VI. 

SPINAL ACCESSOET AXD 8TJBLINGUAL NEBVES. 

Spinal accessory nerve (third division of the eighth) Physiological anatomy- 
Properties and functions of the spinal accessory Functions of the internal 
branch from the spinal accessory to the pneumogastric Influence of the 
spinal accessory upon tlie vocal movements of the larynx Influence of the 
internal branch of the spinal accessory upon deglutition Influence of the 
spinal accessory upon the heart Functions of the external, or. muscular 
branch of the spinal accessory Sublingual, or hypoglossal nexve (ninth) 
Physiological anatomy Properties and functions of the sublingual Glos- 
so-labial paralysis, 166 



CHAPTER VII. 

TBIFACIAL, OE TBIGEMIXAL XEBVE. 

Physiological anatomy of the trifacial Properties and functions of the trifacial 
Division of the trifacial within the cranial cavity Immediate effects of 
division of the trifacial Remote effects of division of the trifacial Effects 
of division of the trifacial upon the organs of special sense Division of the 
trifacial before and behind the ganglion of Gasser Communication with 
the sympathetic at the ganglion of Gasser Explanation of the phenomena 
of disordered nutrition after division of the trifacial Cases of paralysis of 
the trifacial in the human subject, 184 



CHAPTER VIII. 

PNEUMOGASTBIC, OE PAB VAGTJM NEBVE. 

Pneumogastric nerve (second division of the eighth) Physiological anatomy 
Properties and functions of the pneumogastric General properties of the 
roots Properties and functions of the auricular nerves Properties and 
functions of the pharyngeal nerves Properties and functions of the supe- 
rior laryngeal nerves Properties and functions of the inferior, or recurrent 
laryngeal nerves Properties and functions of the cardiac nerves, and influ- 
ence of the pneumogastrics upon the circulation Depressor-nerve of the 
circulation Properties and functions of the pulmonary branches, and influ- 
ence of the pneumogastrics upon respiration Properties and functions of 
the cesophageal nerves Properties and functions of the abdominal branches 
Influence of the pneumogastrics upon the liver Influence of the pneumo- 
gastrics upon the stomach and intestines Summary of the distribution, 
properties, and functions, of the pneumogastrics, .... 203 



10 CONTENTS. 



CHAPTER IX. 

PHYSIOLOGICAL ANATOMY AND GENEBAL PEOPEETIES OF THE SPINAL 

COED. 

General arrangement of the cerebro-spiual axis Membranes of the encephalon 
and spinal cord Cephalo-rachidian fluid Physiological anatomy of the 
spinal cord Direction of the fibres after they have penetrated the cord by 
the roots of the spinal nerves General properties of the spinal cord 
Effects of stimulation applied directly to different portions of the 
cord, Page 257 



CHAPTER X. 

ACTION OF THE SPINAL COED AS A CONDUCTOE. 

Transmission of motor stimulus in the cord Decussation of the motor conduct- 
ors of the cord Decussation at the medulla oblongata Decussation of the 
motor conductors in the cervical portion of the cord Transmission of sen- 
sory impressions in the cord The white substance of the posterior columns 
does not conduct sensory impressions Action of the gray matter as a 
conductor Probable function of the cord in connection with muscular 
coordination Decussation of the sensory conductors of the cord Summary 
of the action.of the cord as a conductor, 279 



CHAPTER XI. 

ACTION OF THE SPINAL COED AS A NEEVE-CEXTEE. 

Movements in decapitated animals Definition and applications of the term 
" reflex " Reflex action of the spinal cord History of the discovery of 
so-called reflex action Question of sensation and volition in frogs after 
decapitation Character of movements following irritation of the surface 
in decapitated animals Dispersion of impressions in the cord Conditions 
essential to the manifestation of reflex phenomena Exaggeration of reflex 
excitability by decapitation, poisoning with strychnine, etc. Reflex phe- 
nomena observed in the human subject, 298 



CHAPTER XII. 

THE CEEEBEAL HEMISPHEEES. 

Physiological divisions of the encephalon Weight of different parts of the 
brain and of the entire encephalon Some points in the physiological anat- 



CONTEXTS. 11 

orny of the encephalon and its connections The cerebrum General prop- 
erties of the cerebrum Functions of the cerebrum Extirpation of the 
cerebrum in animals Pathological facts bearing upon the functions of 
the cerebrum Comparative development of the cerebrum in the lower 
animals Development of the cerebrum in different races of men and in 
different individuals Ethnological table, derived from autopsies of white 
and negro brains Table of weights of the encephalon in different indi- 
viduals Location of the faculty of articulate language hi a restricted por- 
tion of the anterior cerebral lobes, Page 313 



CHAPTER XIII. 

THE CEREBELLUM. 

Some points in the physiological anatomy of the cerebellum Course of the 
fibres in the cerebellum General properties of the cerebellum Functions 
of the cerebellum Extirpation of the cerebellum in animals Incomplete 
extirpation of the cerebellum Pathological facts bearing upon the func- 
tions of the cerebellum Andral's cases Other cases of disease of the 
cerebellum Connection of the cerebellum with the generative function 
Development of the cerebellum in the lower animals Paralysis from disease 
or injury of the cerebellum, 359 

CHAPTER XIY. 

GANGLIA AT THE BASE OF THE EXCEPHALOX. 

Corpora striata Optic thalami Tubercula quadrigemina, or optic lobes Gan- 
glion of the tuber annulare Medulla oblongata Physiological anatomy of 
the medulla oblongata Functions of the medulla oblongata Connection 
of the medulla oblongata with respiration Vital point Connection of the 
medulla oblongata with various reflex acts Rolling and turning movements 
following injury of certain parts of the encephalon General properties of 
the peduncles, 393 

CHAPTER XV. 

SYMPATHETIC XEBYOrS SYSTEM:. 

General arrangement of the sympathetic system Peculiarities in the intimate 
structure of the sympathetic ganglia and nerves General properties of the 
sympathetic ganglia and nerves Functions of the sympathetic system 
Yaso-motor nerves Reflex phenomena operating through the sympathetic 
system Trophic centres and nerves, so called, .... 416 



12 CONTENTS. 

CHAPTER XVI. 

SLEEP. 

General considerations Condition of the organism during sleep Dreams Re- 
flex mental phenomena during sleep Condition of the brain and nervous 
system during sleep Theories of sleep Anaesthesia and sleep produced 
by pressure upon the carotid arteries Differences between natural sleep, 
and st'jpor and coma Regeneration of the brain-substance during sleep 
Theory that sleep is due to a want of oxygen Condition of the various 
functions of the organism during sleep, Page 446 



PHYSIOLOGY OF MAN. 



CHAPTER I. 

PHYSIOLOGICAL DIVISIONS AND STRUCTURE OF THE NERVOUS 

SYSTEM. 

General considerations Divisions of the nervous system Physiological anatomy 
of the nervous tissue Anatomical divisions of the nervous tissue Medul- 
lated nerve-fibres Simple, or non-medullated nerve-fibres Gelatinous 
nerve-fibres (fibres of Remak) Accessory anatomical elements of the 
nerves Branching and course of the nerves Termination of the nerves 
in the muscular tissue Termination of the nerves in glands Terminations 
of the sensory nerves-r- Corpuscles of Pacini, or of Yater Tactile corpus- 
cles Terminal bulbs Structure of the nerve-centres Nerve-cells Con- 
nection of the cells with the fibres and with each other Accessory anatom- 
ical elements of the nerve-centres Composition of the nervous substance 
Regeneration of the nervous tissue Reunion of nerve-fibres. 

THE nervous system is anatomically distinct in all ani- 
mals, except those lowest in the scale of being. It is useless 
to speculate upon the question of the existence of matter en- 
dowed with properties analogous to those observed in the 
nervous system of the higher animals, in beings so low in 
their organization as to present no, divisions into anatomical 
elements ; for the present condition of physiological science 
does not admit of the recognition of functions without organs. 
All animals that present any thing like nervous functions pre- 
sent also an anatomically distinct nervous system. "Within 
certain limits, the perfection of the animal organization de- 
pends upon the general development of the nervous system. 

High in the animal scale, as in the warm-blooded ani- 



NEKVOTJS SYSTEM. 

j the general development of this system presents little, 
if any, variation ; but special attributes are coexistent with 
the development of special organs. The development in 
this way of particular portions of the nervous system is in 
accordance with the particular conditions of existence of 
different animals ; it is a necessary part of their organiza- 
tion, and is not dependent upon education or intelligence. 
Examples of this are in the extraordinary development of 
the sense of sight, hearing, or smell, in different animals. 
There are animals in which these special senses possess a 
delicacy of perception to which man, even with the greatest 
amount of intelligent education, can never attain ; but man, 
possessing a nervous organization not superior to that of 
other warm-blooded animals in its general development, 
and inferior to many in the development of special organs, 
stands immeasurably above all other beings, by virtue of 
the immense preponderance of what is known as the en- 
cephalic portion of the nervous system. 

These brief general considerations will convey some idea 
of the physiological importance of the nervous system ; of 
the care which should be exercised in its study ; and of the 
great interest attached to it, from the fact that the most 
complex and important of its functions belong to human 
physiology, and to human physiology alone. 

"We can best define what is to be included under the 
head of the nervous system, by citing certain of its prominent 
and well-established properties and functions. 

1. The nervous system is anatomically and physiologi- 
cally distinct from all other systems and organs in the body. 
It receives impressions made upon the terminal branches of 
its sensory portion, it conveys stimulus to parts, determining 
and regulating the operation of their functions; but its 
physiological properties are inherent, and it gives to no tis- 
sue or organ its special " irritability " or the power of per- 
forming its particular function. 1 

1 We have already discussed the independence of what is called "nervous 



DIVISIONS OF THE NERVOUS SYSTEM. 15 

2. The nervous system connects into a coordinated or- 
ganism every part of the body. It is the medium through 
which all impressions are received. It animates or regulates 
all movements, voluntary and involuntary. It regulates the 
functions of secretion, nutrition, calorification, and all the 
processes of organic life. 

In addition to its functions as a medium of conduction 
and communication, the nervous system, in certain -of its 
parts, is capable of receiving impressions and of generating 
a stimulating influence, or force, peculiar to itself. As there 
can be no physiological connection or coordination of differ- 
ent parts of the organism, having an active function, without 
nerves, there can be no unconscious reception of impressions 
giving rise to involuntary movements, no appreciation of 
impressions, general, as in ordinary sensation, or special, as 
in sight, smell, taste, or hearing, no instinct, volition, 
thought, or even knowledge of existence, without nerve- 
centres. * 

Possessing, as it does, these varied properties and func- 
tions, it is evidently of the greatest physiological importance 
that the anatomical characters of the nervous system should 
be most carefully studied, with a view, if possible, of con- 
necting certain of the nervous properties with peculiarities 
in structure. It is also important to subdivide the system, 
as regards general properties and functions, as well as with 
reference to the special office of particular parts. With this 
end in view, we will point out, first, the great anatomico- 
physiological divisions common to nervous matter wherever 
it exists, and afterward, the subdivisions of the system as re- 
gards special functions. 

Divisions of the Nervous System. 

Nervous matter, whatever may be its special function, 
presents two great divisions, each with distinct anatomical 

irritability," in treating of the properties of the muscles. See vol. iii., Move- 
ments, p. 463. 

102 



16 NERVOUS SYSTEM. 

as well as physiological differences.' One of these divisions 
presents the form of fibres, or tubes. This kind of nervous 
matter is incapable of generating a force or stimulus, and 
serves onl j as a conductor. The other division is in the 
form of cells, and this kind of nervous matter alone is capa- 
ble of generating the so-called nervous force. 

The nervous matter is divided into two great systems, as 
follows : 

1. The cerebro-spinal system, composed of the brain and 
spinal cord with the nerves directly connected with these cen- 
tres. This system is specially connected with the functions 
of relation, or of animal life. The centres preside over gen- 
eral sensation, the special senses, voluntary and some invol- 
untary movements, intellection, and, in short, all of the func- 
tions that characterize the animal. The nerves serve as the 
conductors of impressions known as general or special sen- 
sations, and of the stimulus that gives rise to voluntary and 
certain involuntary movements, the latter being the auto- 
matic movements connected with animal life. 

2. The sympathetic, or organic system. This system is 
specially connected with the functions relating to nutrition, 
operations which have their analogue in the vegetable king- 
dom, and are sometimes called the functions of vegetative 
life. Although this system presides over functions entirely 
distinct from those characteristic of and peculiar to animals, 
the centres of this system all have an anatomical and phys- 
iological connection with the cerebro-spinal nerves. 

The cerebro-spinal system is subdivided into centres pre- 
siding over movements and ordinary sensation, and centres 
capable of receiving impressions connected with the special 
senses, such as sight, audition, olfaction, and gustation. The 
nerves which receive these special impressions and convey 
them to the appropriate centres are more or less insensible 
to ordinary impressions. The organs to which these special 
nerves are distributed are generally of a complex and pecul- 
iar structure, and present numerous accessory parts which 



ANATOMY OF THE NERVOUS TISSUE. 17 

are important and essential in the transmission of the special 
impressions to the terminal branches of the nerves. 

In treating of the nervous system, we will consider first 
the physiological anatomy of the nervous tissue ; next, the 
general properties of the cerebro-spinal system ; next, the 
functions of different portions of this system connected with 
motion, ordinary sensibility, intellection, etc. ; next, the func- 
tions of the sympathetic, or organic system of nerves ; and 
finally, the special senses, with the physiological anatomy 
and mechanism of the accessory parts. 1 

Physiological Anatomy of the Nervous Tissue. 

The physiological anatomy of the nervous system natu- 
ally divides itself into two sections ; one embracing what is 
called the general anatomy of the nervous tissue, and the 
other, the arrangement of this tissue in special organs, as 
far as this is connected with their functions. 

The intimate structure of the different portions of the 
nervous system may now be regarded as tolerably well un- 
derstood, at least as far as those anatomical points bearing 
on physiology are concerned. The connection between the 
nerve-cells and the fibres and the modes of termination of the 
motor filaments in the muscles are points nearly, if not quite, 
settled ; and the terminations of sensory filaments in integu- 
ment and mucous membranes have lately been investigated 
very thoroughly, and with quite positive and satisfactory re- 
sults. These anatomical points are especially connected with 
the general properties of the nervous system, both as a gen- 
erator of the so-called nerve-force and as a conductor. 

The arrangement of the nervous elements in special or- 
gans, as in the brain and spinal cord, has not been so suc- 
cessfully investigated, and presents immense difficulties in 
its study ; and we can hardly hope to acquire any thing like 

1 The special senses will be fully considered in the fifth and last volume of 
this series. 



18 NEKVOUS SYSTEM. 

a definite and thorough knowledge of the functions of these 
parts, until we have much more positive information con- 
cerning their anatomical characters. 

Anatomical Divisions of the Nervous Tissue. The phys- 
iological division of the nervous system into nerves and 
nerve-centres is pretty well carried out as regards the ana- 
tomical structure of these parts. The two great divisions of 
the system, anatomically considered, are into nerve-cells and 
nerve-fibres. 

The nerve-cells, as far as we know, are the only parts 
capable, under any circumstances, of generating the nerve- 
force ; and, as a rule, they cannot receive impressions in any 
other way than through the nerve-fibres. There are, how- 
ever, some exceptions, either apparent or real, to this rule, 
as in the case of direct irritation of the ganglion of the tuber 
annulare, 'and the sympathetic ganglia, which seem sensible 
to direct irritation ; but the cells of most of the ganglia be- 
longing to the great cerebro-spinal axis are insensible to 
direct stimulation and will only receive impressions con- 
ducted to them by the nerves. 

The nerve-fibres act only as conductors, and are incapa- 
ble of generating nerve-force. There is no exception to this 
rule, but there are differences in the properties of certain 
fibres. The nerves generally, for example, will receive di- 
rect impressions, the motor filaments conducting these to 
the muscles and the sensory filaments conveying the im- 
pressions to the centres. These fibres will also conduct the 
force generated by the nerve-centres. But there are many 
fibres, such as those composing the white matter of the 
encephalon and the spinal cord, that are insensible to direct 
irritation, while they will convey to the centres impressions 
made by the sensitive nerves, and will conduct to the motor 
nerves stimulus generated by nerve-cells. 

Structure of the Nerves. There are few anatomical ele- 



MEDULLATED XERVE-FIBRES. 19 

ments that present greater variations in size and appearance 
than the nerve-fibres. Certain fibres found in the course of 
the nerves between the muscles are as large as y^Vrr f an 
inch, have dark borders, and possess three well-marked 
structures ; viz., a tubular membrane, medullary contents, 
and an axial band ; others, with the same structure, are only 
saooo of an inch in diameter ; others have only the medul- 
lary covering and the axial band ; and others present the 
axial band alone. Most of these anatomical elements have 
essentially the same physiological conducting properties; 
the variations in their structure depending upon differences 
in their anatomical relations. In view of these facts, it will 
be convenient to adopt some anatomical classification of the 
fibres. 

In the most simple classification of the nerve-fibres, they 
are divided into two groups; one embracing those fibres 
which have the conducting element alone, and the other 
presenting this element surrounded by certain accessory 
structures. In the course of the nerves, the simple fibres are 
the exception, and the other variety is the rule ; but as the 
nerves are followed to their terminations in muscles or sensi- 
tive parts, or are traced to their origin in the nerve-centres, 
we find that they lose one or another of their adventitious 
elements. These two varieties we shall term : 1. The me- 
dullated fibres, and 2. The simple, or non-medullated fibres. 



nUated Nerve-fbres. These fibres are so called by 
French and German writers because, in addition to the axis- 
cylinder, or conducting element, they contain, enclosed in a 
tubular sheath, a soft substance called the medulla. This 
substance is strongly refractive and gives the nerves a pecu- 
liar appearance under the microscope, from which they are 
sometimes called the dark-bordered nerve-fibres. . As the 
whole substance of the fibre is enclosed in a tubular mem- 
brane, these are frequently spoken of as nerve-tubes. 

If the nerves be examined while perfectly fresh and un- 



20 NERVOUS SYSTEM. 

changed, their anatomical elements appear in the form of 
simple fibres with strongly accentuated borders. The diam- 
eter of these fibres is from ^fa to -p^Vo" of an inch. 1 To 
observe the fibres in this way, it is necessary to take a nerve 
from an animal just killed and examine it without delay. 
In. a very short time the borders become darker and the 
fibre assumes an entirely different appearance. By the use 
of certain reagents, it can be demonstrated that a medullated 
nerve-fibre is composed of three distinct portions ; viz., a 
homogeneous sheath, a semi-fluid matter contained in the 
sheath, and a delicate central band. 

The tubular sheath of the nerve-fibres is a somewhat elas- 
tic, homogeneous membrane, never striated or fibrillated, 
and presenting generally oval nuclei, with their long diam- 
eter in the direction of the tube. This is sometimes called 
the neurilemma, a name, however, which is more generally 
applied to another membrane. It is sometimes spoken of, 
also, as the " limiting membrane of Valentin," or " the sheath 
of Schwann." In its chemical and general properties, this 
membrane resembles the sarcolemma, though it is less elas- 
tic and resisting. It exists in all the medullated nerve-fibres, 
large and small, except those in the white portions of the 
encephalon and spinal cord. It is not certain that it does not 
exist in the small, non-medullated fibres, though its presence 
here has never been satisfactorily demonstrated. 2 As we 
before remarked, the tubular membrane cannot be seen in 
the perfectly fresh nerves ; and even after they have become 
changed by desiccation, its demonstration requires the use of 
reagents. In the ordinary medullated fibres, however, it 
may be isolated by boiling the nerve in absolute alcohol and 
then in acetic acid, or by treating it with cold caustic soda. 
By then boiling the nerve for an instant in the caustic soda, 
fragments of the tube may be isolated, when they resemble 
the membrane forming the canals of the kidney. Another 

1 LITTRE ET ROBIN, Didionnaire de mededne, Paris, 1865, Article, Nerveux. 
9 KOLLIKER, Element cPhistologie humaine, Paris, 1868, p. 315. 



MEDULLATED NERVE-FIBRES. 21 

method is to treat the nerve with fuming nitric acid, after- 
ward adding a solution of caustic potash. The fatty sub- 
stance is thus discharged in small drops, the central band is 
dissolved, and the empty sheath is seen, swollen and tinged 
with yellow. These are the processes employed by Kolliker, 
who demonstrates in this way the presence of nuclei. 1 

The medullary substance fills the tube and surrounds the 
central band. This is called by various names ; as myeline, 
white substance of Schwann, medullary sheath, nervous me- 
dulla, etc. It does not exist either at the origin of the nerves 
in the gray substance of the nerve-centres or at the periphe- 
ral termination of the nerves, and is probably not an essential 
conducting element. When the nerves are perfectly fresh, 
this substance is transparent, homogeneous, and strongly 
refracting, like oil ; but as the nerves become altered by des- 
iccation, the action of water, acetic acid, and various other 
reagents, it coagulates into an opaque, granular mass. The 
consistence of this substance gives to the medullated fibres a 
very peculiar appearance. The tubular membrane being 
very thin and not elastic, the white substance, by very slight 
pressure, is made to fill the tubes irregularly, giving them a 
varicose appearance, which is entirely characteristic. In ex- 
amining a preparation of the nervous tissue, large drops, 
coagulated in irregular shapes, are seen scattered over the 
field, and frequently fringing the divided ends of the tubes, 
In the white substance of the encephalon and spinal cord, 
where the tubular membrane is wanting, the varicose appear- 
ance of the fibres is more remarkable than in any other situ- 
ation. 

The axis-cylinder is, in all probability, the essential ana- 
tomical element of the nerves. It exists in all the nerves 
except in those termed gelatinous fibres, or fibres of Eemak, 
which will be described hereafter. In the ordinary medul- 
lated fibres, the axis-cylinder cannot be seen in the natural 
condition of the tissue, because it refracts in the same man- 

1 KOLLIKER, op. tit., p. 318. 



22 NERVOUS SYSTEM. 

ner as the medullary substance, and it cannot "be demon- 
strated afterward, on account of the opacity of the coagulated 
matter. If a fresh nerve, however, be treated with strong 
acetic acid, the divided ends of the fibres will retract, leaving 
the axis-cylinder, which is but slightly affected by reagents. 
It then presents itself in the form of a pale, slightly-flattened 
band, with outlines tolerably regular, though slightly vari- 
cose at intervals, somewhat granular, and sometimes very 
finely striated in a longitudinal direction. This band is 
elastic, but not very resisting. Its granules are excessively 
pale. "What serves to distinguish it from all other portions 
of the nerve-fibre is its insolubility in most of the reagents 
employed in anatomical investigation. It is slightly swollen 
by acetic acid, but is dissolved after prolonged boiling. If 
a solution of carmine be added to the nervous tissue, the 
axis-cylinder only is colored. It has been remarked that 
the nerve-fibres treated with nitrate of silver present in the 
axis- cylinder well-marked transverse striations. This was 
observed by Frommann, 1 and has since been confirmed by 
Grandry. 3 The latter observer is disposed to regard both 
the nerve-cells and the axes of the fibres as composed of two 
substances, the limits of which are marked by the regular 
striae developed by the nitrate of silver. This, however, is 
a point of purely anatomical interest. The presence of regu- 
lar and well-marked striae in the axis-cylinder after the addi- 
tion of a solution of nitrate of silver and the action of light 
cannot be doubted ; but it has not yet been determined be- 
yond question whether these markings be entirely artificial, 
or whether the axis-cylinder be really composed of two kinds 
of substance. 

A still more important question with regard to the inti- 

1 FROMMANN, Ueber die Fiirbung-der Binde- und Nervensubstanz des Rucken- 
markes durch Argentum nitricum und uber die Struktur der Nervenzellen. 
Archiv fur pathologische Anatomic und Physiologic, etc.', Berlin, 1864, Bd. xxxi., 
S. 129, et seq. Zur Silberfdrbung der Axencylinder, ibid., S. 151, et seq 

2 GRANDRY, JDe la structure intime du cylindre de Vaxe et des cellules nerveuses. 
Journal de F anatomic, Paris, 1889, tome vi., p. 289, et seq. 



NON-MEDTJLLATED NEBVE-FIBRES. 23 

mate structure of the axis-cylinder refers to the longitudinal 
striations. These are observed in many fibres, but they are 
not constant. Some authors have adopted the view that 
the markings are produced by fibrillse, analogous to the 
fibrillse of the muscular fibres, in all the fibres, as well as in 
those of the retina, 'Olfactory, and some of the sympathetic 
nerves. 1 In the organs of special sense, there can be no 
doubt of the existence of fibrillse ; but this is by no means so 
clearly demonstrable in the general system of nerves. Still, 
it is necessary to take into consideration, in this connection, 
certain facts with regard to the origin of the nerve-fibres in 
the cells and their ultimate distribution in sensitive parts. 
In the final distribution of sensitive nerves, we shall see that 
the fibres break up into filaments resembling fibrillee, and 
although the fibrillated . character of the poles of the nerve- 
cells is not unreservedly accepted by anatomists, many ob- 
servers positively state that such is their structure. In the 
present condition of the science, we cannot do more than 
state that, while a fibrillated structure has perhaps been 
shown in the nerves of some of the lower orders of animals, 
its existence in man and the mammalia is somewhat doubtful. 
The diameter of the axis-cylinder is about one-half or one- 
third that of the tube in which it is contained. The various 
appearances which the nerve-fibres present under different 
conditions are represented in Fig. 1. 

Simple, or Non-meduUated Nerve-Flares. These fibres 
are found very largely distributed in the nervous system. 
In the last edition of what is perhaps the most authoritative 
work on histology, it is stated that " the more we advance 
in our researches, fhe more evident it becomes that, in man 
and the higher classes of animals, nerve-fibres without the 
white substance are very widely distributed." a However, 

1 SCHULTZE, in STRICKER, Manual of Human and Comparative Histology, 
London, 1870, vol. i., p. 147, et seq. 

2 KOLLIKER, op. cit., p. 322. 



21 NERVOUS SYSTEM. 

when we come to study the structure and relations of these 
small fibres, which seem in many instances to be simple 
prolongations, without alteration, of the axis-cylinder of the 
medullated fibres, it will be seen that they are chiefly found 
in the peripheral terminations of the nerves and in the fila- 

FlG.l. 




Nerve-fibres from the human subject, magnified 350 diameters ; four small fibres, of which two 
are varicose, one medium-sized fibre with borders of single contour, and four large fibres; of 
the latter, two have a double contour, and two contain granular matter. (KOLLIKEK, Hand- 
luch der Gewebelehre, Leipzig, 1867, S. 289.) 

ments of connection of the fibres with the cells. The study 
of the fibres in these relations constitutes the most important 
part, physiologically, of the anatomy of the nerves, and pre- 
sents the greatest difficulties in the way of direct observa- 
tion ; and, for that reason, we shall treat of these questions 
separately, and defer until then the full consideration of the 
non-medullated fibres. 

Gelatinous Nerve-Fibres (Fibres of It emetic). These 
fibres are entirely different in their anatomy from either of 
the varieties of fibres just considered. They are found chiefly 
in the sympathetic system, and in that particular portion of 



GELATINOUS NEKVE-FIBRES. 25 

this system connected with involuntary movements. For 
instance, these fibres are very abundant in the gray filaments 
sent to parts provided with non-striated muscular fibres and 
endowed with undoubted motor properties ; but they are not 
found in the white filaments of the sympathetic, which seem 
to be incapable of exciting movements. 1 

There is considerable difference of opinion among physi- 
ologists with regard to the gelatinous filaments. Some are 
disposed to regard them as elements of connective tissue, not 
endowed with properties characteristic of nerves, while others 
consider that they are nerve-fibres, probably possessing func- 
tions distinct from those of the fibres of different structure. 
The first opinion was formerly held by Kolliker, who states, 
in one of the early editions of his work on Microscopic 
Anatomy, that all of the fibres of Remak are " only a form 
of connective tissue ; " 3 but in a later edition, he admits that 
the nucleated fibres of the great sympathetic, which resemble 
embryonic nervous elements, are really nerve-fibres. 8 This 
is the view now adopted by the best anatomists. While it 
is certain that elements of connective tissue exist in the 
nerves, and have been mistaken for true nerve-fibres, there 
are in the nerves, particularly in those belonging to the 
great sympathetic system, fibres exactly resembling the 
nerve-fibres of the embryon. These are the true gelatinous 
nerve-fibres, or fibres of Remak. It is stated that the nerves 
generally have this structure up to the fifth month of intra- 
uterine life, and that in the regeneration of nerves after 
division or injury, the new elements assume this form before 
they arrive at their full development. 4 

The true gelatinous nerve-fibres present the following 
characters: They are flattened, with regular and sharp 
borders, grayish and pale, presenting numerous very fine 

1 REMAK, Observation&s de Sysfematis S"erv. Struct., Berolini, 1838, p. 5. 

2 KOLLIKER, Microscopic Anatomy, London, 1860, p. 254. 

8 KOLLIKER, Cements d"histologie humaine, Paris, 1868, p. 432. 

4 LITTRE ET ROBIN, Dictionnaire de medecine, Paris, 1865, Article, Nerveux. 



26 



NERVOUS SYSTEM. 



FIG. 2. 



granulations, and a number of oval, longitudinal nuclei, a 
characteristic which has given them the name of nucleated 
nerve-fibres. The diameter of the fibres is about -g^or f 
an inch. The nuclei have nearly the same diameter as the 
fibres, and are about y^Vtr of an inch in length ; l they are 
finely granular, and present no nucleoli. The fibres are 
rendered pale by the action of acetic acid, but they are 
slightly swollen only, and present, in this 
regard, a marked contrast with the ele- 
ments of a connective tissue. The micro- 
scopical appearances of these fibres, which 
are strongly characteristic, are represented 
in Fig. 2. 

Accessory Anatomical Elements of the 
Nerves. The nerves present, in addition 
to the different varieties of true nerve- 
fibres just described, certain accessory ana- 
tomical elements common to nearly all of 
the tissues of the organism, such as con- 
nective tissue, blood-vessels, and perhaps 
lymphatics, though these have never been 
demonstrated, except in the nerve-centres. 

Like the muscular tissue, the nerves are 
made up of their true anatomical elements, 
the nerve-fibres, held together into primi- 
tive, secondary, and tertiary bundles, and 

nified 800 diameters. . . . . . r . .^ 

with the gelatinous so on, in proportion to the size ot the nerve. 
of S ordinarydari^ The primitive fasciculi are surrounded by 

bordered nerve-fibres. IT i i ' i -i T> i 

(LITTRE ET KQBIN, a delicate membrane, described by Hob in 

l)ictionnaire de me- -, .-, /,/.* 01^ -i i 

1865, p. under the name ot pertnevre, but which 
had been already noted by other anato- 
mists under different names. 3 This membrane is homoe- 




mag- 






1 LITTRE ET ROBIN, loc. tit. 

2 LITTRE ET ROBIN, Dictionnaire de mededne, Paris, 1865, Article, Fcrinevre. 
8 KOLLIKER, Elements (Thistelcgie humainc, Paris, 18G8, p. 317. 



ACCESSORY ANATOMICAL ELEMENTS. 27 

neons or very finely granular, sometimes marked with longi- 
tudinal striae, and possessing elongated nuclei, finely granular, 
from ^Vo- to TOTRT f an inc h in length by from ^Vir to 
TTOTF f an mc ^ wide. The thickness of the membrane is 
from I2 ooo to -g^nj-Q of an inch. It commences at the point 
where the nerve-fibres emerge from the white portion of the 
nervous centres, and extends to their terminal extremities, 
being interrupted by the ganglia in the course of the nerves. 
This membrane generally envelops a primitive fasciculus of 
fibres, branching as the bundles divide and pass from one 
trunk to another; but it is sometimes found surrounding 
single fibres. An important anatomical fact connected with 
this membrane is that it is never penetrated by blood-vessels, 
the smallest capillaries of the nerves ramifying in its sub- 
stance, but never passing through to the individual nerve- 
fibres. Within the perinerve, are sometimes found ele- 
ments of connective tissue, but never any other of the ac- 
cessory anatomical elements of the nerves. 1 

The amount of fibrous tissue in the different nerves is very- 
variable and depends upon the external conditions to which 
they are subjected. In the nerves within the bony cavities, 
where they are entirely protected, the fibrous tissue is very- 
scanty ; but in the nerves between muscles, we find a toler- 
ably strong investing membrane, or sheath surrounding the 
whole nerve and sending processes into its interior, which 
envelop smaller bundles of fibres. This sheath is formed of 
inelastic fibres with small elastic fibres and nucleated con- 
nective-tissue fibres. These latter may be distinguished 
from the gelatinous nerve-fibres by the action of acetic acid, 
which swells and finally dissolves them, while the nerve- 
fibres are but slightly affected. 

The late researches of Sappey have shown that the struct- 
ure of the fibrous sheath of the nerves possesses certain 
important anatomical peculiarities. The greatest part of 
this membrane is composed of bundles of white, inelastic 

1 LlTTRE ET ROBIX, loc. tit. 



28 NERVOUS SYSTEM. 

tissue, interlacing in every direction ; but it contains also 
numerous elastic fibres, adipose tissue, a net-work of arteries 
and veins, and " nervi-nervorum" which are to these struct- 
ures what the vasa-vasorum are to the vessels. The adipose 
tissue is constant, being found even in extremely emaciated 
persons. 1 

The vascular supply to most of the nerves is rather scan- 
ty. The arteries break up into a plexus of very fine capil- 
laries, arranged in oblong, longitudinal meshes surrounding 
the fasciculi of fibres ; but they never penetrate the peri- 
nerve and come in contact with the ultimate nervous ele- 
ments. The veins are rather more voluminous, and follow 
the arrangement of the arteries. It is not certain that the 
nerves in their course contain lymphatics ; at least these ves- 
sels have never been demonstrated in their substance. 

Branching and Course of the Nerves. The ultimate 
nerve-fibres in the course of the nerves have no connection 
with each other by branching or inosculation. A bundle of 
fibres frequently sends branches to other nerves and receives 
branches in the same way ; but this is simply the passage of 
fibres from one sheath to another ; the ultimate fibres them- 
selves maintaining throughout their course their integrity 
and individual physiological properties. This view with 
regard to the course of the fibres in the nerves is held by 
nearly all anatomists. Some, however, assert that branch- 
ing and inosculation of individual fibres sometimes occur in 
the course of nerves ; a but this statement is not sufficiently 
confirmed, in view of the very general opinion to the con- 
trary. It has long been known, since the researches of Savi, 
Robin, "Wagner, and others, that in the electric organs of 
certain fishes, the large nerve-fibres break up into numerous 

1 SAPPEY, Recherches sur la structure de T envelope fibreuse des nerfs. Journal 
de Panatomie, Paris, 1868, tome v., p. 47, et seq. 

8 SCHDLTZE, in STRICKER, Handbuch der Lehre von den Geweben, Leipzig, 1 868, 
S. 119. 



TERMINATION OF NEKVES EST MUSCLES. 29 

oranclies before they pass to their termination ; * but there 
is no such arrangement in the human subject or in the high- 
er animals, in the course of the nerves, or anywhere, except 
at the point where the fibres change their character just be- 
fore their termination. The branching and inosculation of 
the ultimate nerve-fibres will be considered in connection 
with the very interesting and important question of their 
ultimate distribution to muscles and sensitive parts. 

Mode of Termination of the Nerves in the Voluntary 
Muscles. For a long time the actual mode of termination 
of the nerve-fibres in the muscles was a question of great 
uncertainty ; but within the last few years, thanks to the 
elaborate researches of the French and German anatomists, 
the peripheral extremities of the nerves have been so accu- 
rately described and figured, that the great question of the 
mode of connection between the anatomical element con- 
ducting the stimulus to the muscles and the contractile 
elements of the muscles themselves may be considered as 
definitively settled. So many views, however, have been 
presented on this subject from time to time, that an histori- 
cal account of the numerous researches, within even the last 
few years, would possess but little physiological interest. 3 

Before physiologists had any definite knowledge of the 
true mode of termination of the motor nerves, the only 
opinion on this subject entitled to any consideration was 
that of Prevost and Dumas, who believed that they had de- 

1 ROBIN, Jfemoire sitr la demonstration experimentale de la production d'electri- 
cite par un appareil propre aux poissons du genre des raies. Journal de Vana- 
tomie, Paris, 1865, tome ii., p. 533, et seq. 

2 Prof. Trinchese, in an historical introduction to an account of his own 
observations on the peripheral termination of the nerves, gives an admirable 
review of recent researches on this subject. He is in error, however, in dating 
the view of the termination in loops from Valentin and Emmert, in 1836, this 
theory having been advanced by Prevost and Dumas, in 1823. (TRIXCHESE, Me- 
moire sur la terminaison peri.pherique des nerfs moteurs. Journal de fanatomie, 
Paris, 1867, tome iv., p. 485, et seq.} 



30 NERVOUS SYSTEM. 

monstrated loops at the peripheral ends of the nerves resting 
on the muscular fibres. These loops were fully described and 
figured in 1823, 1 and this view was afterward quite gener- 
ally adopted by physiologists ; but it has been so completely 
overthrown by recent observations, that it is not now a ques- 
tion for discussion. In 1840, Doyere gave an account of the 
peripheral termination of the motor-nerves, 3 probably as 
accurate as was possible with his imperfect means of in- 
vestigation ; but, as is justly remarked by Prof. Trinchese, 
this observation, though confirmed a few years later by 
Quatrefages, 8 seems to have been lost sight of by most phys- 
iological writers. 4 In view of these early researches, it is 
unnecessary to consider elaborately the claims to priority of 
more recent observers, the results of whose investigations 
present slight and unimportant differences ; and, although 
these have been brought forward and warmly discussed 6 as 
a matter of controversy, they possess but little interest. 

"We shall not enter into any further discussion of the 
views expressed by different anatomists with regard to the 
question under consideration, but will now simply describe 
the connection between the peripheral nerves and the mus- 
cles, as it appears from the researches that seem to be the 
most exact and reliable. Without underestimating the value 
of other researches, we may state that those of Rouget repre- 
sent, perhaps, the present condition of the question as well as 
any. As we before remarked, the differences between the 

1 PREVOST ET DUMAS, Memoire sur left phenomenes qui accompagnent la con- 
traction de la fibre musculaire. Journal de physiologic, Paris, 1823, tome iii., 
p. 322. 

2 DOYERE, Memoire sur les tardigrades. Annales des sciences naturelles, Zoo- 
Ugie, Paris, 1840, tome xiv., p. 346. 

3 QUATREFAGES, Memoire sur Veolidine paradoxale. Annales des sciences na- 
turelles, Zoologie, Paris, 1843, tome xix., p. 300. 

4 JTrinchese (loc. cit.) alludes to the observations of Doyere, which are also 
fully discussed by Kuhne (STRICKER, Handbuch der Lehre von den Geweben, Leip- 
zig, 1868, S. 147, et seq.). 

5 BEALE, An Anatomical Controversy. The Distribution of Nerves in Volun- 
tary Muscle, etc., London, 1865, pp. 38. 



TERMINATION OF NERVES EST MUSCLES. 31 

most reliable observations of recent writers are nearly all 
unimportant; and while future investigations may enable 
us to go further in following some of the elements of the 
nerve-fibres, they will, in all probability, simply extend our 
knowledge without invalidating the information already ac- 
quired. 

The observations of Eouget were published in 1862, and 
were made upon lizards, frogs, Guinea-pigs, rats, and other 
animals, and confirmed in the human subject. 1 The tis- 
sues were taken either from the living animal or from an 
animal just killed, and were examined, in some instances, 
without the addition of reagents ; but the most satisfactory 
results were obtained by macerating the muscles for from six 
to twenty-four hours in a liquid containing j^Vo" f hydro- 
chloric acid, and adding to the preparation on the glass slide 
a drop of a solution of sugar in water. In preparations made 
in this way, it is easy to trace the course of the nerves to 
their termination. The following is the description given 
by Rouget-: 

" The nervous trunks and the branches of distribution 
generally cross the course of the' muscular fibres. As re- 
gards the terminal ramifications, sometimes they meet the 
muscular fibres at nearly a right angle, and sometimes they 
are placed nearly parallel to the axis of the primitive fascic- 
uli. Branches of distribution are detached sometimes from 
branches containing two or three fibres, and sometimes from 
isolated fibres. After a very short course these tubes divide, 
and may present as many as seven or eight successive divis- 
ions. Most commonly, the termination takes place either 
by divisions of the second or third order, or the same tube 
gives off, successively, divisions which pass to the adjacent 
primitive fasciculi and terminate here without new divisions 
and after a very short course. They have a less diameter 

1 ROUGET, Memoire sur la termination des nerfs moteurs dans les muscles chez 
les reptiles, les oiseaux et les mammiferes. Journal de la physiologic, Paris, 1862, 
tome v., p. 574, et seq. 
103 



32 NERVOUS SYSTEM. 

than the primitive nerve-tubes, but they preserve even tc 
the terminal extremity their double contour, and there can 
be demonstrated, very easily, a sheath provided with nuclei, 
a medullary layer, and the axis-cylinder. Never do we ob- 
serve at the termination of the motor nerves the pale and 
non-medullated fibres described by Kuhne and Kolliker. 
At the point where the tube terminates, we remark con- 
stantly a special arrangement which has no analogy with 
that which has been described in the batrachia by these two 
observers, and which Kuhne believed could be extended to 
the higher vertebrata, to the mammalia, and to the human 
subject. The nerve-tube, with a double contour, preserving 
still a diameter of from -g^-^ to -g^Vir f an mcn a * ^he point 
where it touches the primitive fasciculus to become arrested 
at its surface, terminates by an expansion of the central 
nerve-substance, the axis-cylinder, which is in immediate 
contact with the contractile fibres (fibrillse) of the primitive 
fasciculus. The layer of medullary substance ceases ab- 
ruptly at this point, the sheath of the tube is spread out and 
blended with the sarcolemma ; but in immediate continuity 
with the axis-cylinder, a layer, a plate of granular substance, 
from -g-jnnr to ^-g-j-o ^ an mcn m thickness, is spread out be- 
neath the sarcolemma, on the surface of the fibrillse, in a space 
generally oval and about y^Vo f an mcn wide in its short 
diameter, and -g-J-^- of 3n inch in its long diameter. This 
granular substance masks more or less completely, in the 
space which corresponds to it, the transverse strige of the 
muscular fasciculus. The disk itself has exactly the granu- 
lar appearance of the substance of the axis-cylinder in the 
vertebrata, and of that of the nerve-tubes in most of the inver- 
tebrata, especially after being treated by diluted acids. But 
that which essentially characterizes the terminal plates of the 
motor nerves is an agglomeration of nuclei observed at 
their site. "With a low magnifying power, even, we can dis- 
tinguish the point where a nerve-tube touches the primi- 
tive fasciculus to which it belongs, and ends abruptly at its 



TEEMDxATION OF NERVES IX MUSCLES. 33 

surface, by a collection of from six to twelve or even sixteen 
nuclei which occupy the site of the terminal plate. These nu- 
clei are distinguished by their size as well as by their form, 
which is less elongated than the nuclei of the muscular 
tissue (connective-tissue nuclei of the primitive fasciculi). 
They present, however, the most complete analogy with the 
nuclei of the nerve-sheath (connective-tissue nuclei of the 
newes). They are, without any doubt, nothing else than 
the nuclei which, scattered throughout the entire length of 
the sheath, are collected in a mass at the point where the 
covering of the nerve-fibre is spread out and fuses with the 
sarcolemma of the primitive fasciculus." 

There can be little if any doubt that the description just 
given represents the mode of termination of the nerves in 
the voluntary muscles in man and the mammalia. The ob- 
servations of Kolliker, 1 who describes a plexus of pale fibres 
with nuclei instead of a well-defined terminal plate, were 
made upon frogs, and are probably correct ; and Kolliker ad- 
mits the accuracy of the observations of Rouget as regards 
reptiles, birds, and the mammalia. 11 The views of Beale 3 are 
only entitled to consideration in so far as they confirm previ- 
ous observations. His descriptions and figures, as far as we 
know, are not accepted, nor have they been confirmed by 
any anatomist who has investigated the subject. The ap- 
pearances of the terminal plates are represented in Fig. 3. 

Although the sensibility of the muscles is slight as com- 
pared with that of the tegumentary tissues, they undoubtedly 
possess nerve-fibres other than those exclusively devoted to 
motion. In addition to the fibres just described, Kolliker 
and some others have noted fibres with a different mode of 
termination. These Kolliker believes to be sensitive nerves, 
and their mode of termination has not been so definitely de- 
scribed as in the fibres with terminal motor plates. ^We 
refrain from giving a very full description even of what has 

1 KOLLIKER, Clements d^histologie humaine, Paris, 1868, p. 222, et seg. 

2 KOLLIKER, op. 7., p. 225. 3 Loc, cit. 



M NERVOUS SYSTEM. 

been observed with regard to the termination of these fibres, 
for future and more successful researches will probably mod- 
ify the views now held with regard to this point. Kolliker ' 
states that the fibres in question are very fine, dark-bordered 
tubes, with a medulla ted sheath, which, when studied in 





Mode of termination of the motor nerves, after Booget 

of tiHj thrro^Ttwl muscle o* the ham rabjectMidit? 
ahv ftadnta: ft.tri4*l; & medullary substam* of the tube, which 
to the terminal plate, where it disappears; 4 




of the feud, in which a nerve-tube tenm- 
of the sheath: 8, 3, samfemma becoming 
. : ::.r Mrr-nhc 




nates. 1.1. sheath of the nerve-tube :i 
continue* with the sheath 
the site of the terminal pbte: 5.5. 
sahstance which farms the principal 
r;** 1 ^ 1 ^ 



muscular tissue rendered pale by acetic acid, may be seen to 
give off exceedingly fine, non-medullated fibres, which ter- 
minate in fibres of the same appearance, but provided 
nuclei. It does not .appear to be certain how these fibres 
end. Kolliker is not satisfied that the free extremit: 
they appear to be, are the actual terminations ; but he as- 
serts that in some rare instances they communicate with 
each other. For the present this point must be considered 
as unsettled. 

Mode of Termination of the Werres in the . +ary 

Muscular Tissue. The nerves have not been followed out 

1 KOUJKEK, op. at., p. 228. 



TERMINATION OF NERVES IN GLANDS. 35 

BO satisfactorily in the involuntary as in the striated muscu- 
lar system ; and as most, if not all of the fibres are derived 
from the sympathetic system, which contains numerous 
fibres of Remak the terminations of which have not been 
described, it is evident that our information concerning this 
part of the peripheral nervous system must be incomplete. 
Perhaps the most remarkable of the late observations upon 
this point are those of Dr. Frankenhaeuser, upon the nerves 
of the uterus. These researches were very elaborate ; but 
the point most interesting in this connection is that the 
nerves, having formed a plexus in the connective tissue, send 
exceedingly small fibres into the sheets or layers of muscu- 
lar-fibre cells, which branch and finally go into the nucleoli 
of these structures. 1 Arnold has confirmed these observa- 
tions, and has shown farther that in many instances the fine 
terminal nerve-fibres branch and go into the nuclei of the 
muscular fibres, and then pass out to join with other fibres 
and form a plexus. 8 

Termination of the Newes in Glands. The great in- 
fluence which the nervous system exerts upon secretion at- 
taches considerable interest to recent researches into the 
ultimate distribution of the nerves in the glands. It must 
be remembered, however, in these, as in all observations 
upon the destination of the smallest nerve-fibres, that the 
problem is one of the most difficult in the whole range of 
minute anatomy ; and the results arrived at must be received 

1 FRAXKENHAEUSER, Die Nerven der Gebaermutter und ihre Endigung in den 
glatten ITuskel-fasern, Jena, 1867, S. 76, Taf. viii. 

8 ARNOLD, in STRICKER, Manual of Human, and Comparative Histology, Lon- 
don, 1870, vol. i., p. 195, et seg. The exact mode of termination of the nerves 
in the organic muscles cannot be regarded as definitively settled. We have at- 
tempted, however, to give what seem to be the most reliable views on this sub- 
ject, deduced from recent observations. For a further discussion of some of 
the points which we have accepted as probable, the reader is referred to a recent 
article by Krause. (Die Nervenendigung in den glatten Muskelen. Archiv fur 
Anatomic, Physiologic und wissenschaftliche Medicin, Leipzig, 1870, S. 1, et seg.) 



36 NERVOUS SYSTEM. 

with a certain amount of caution, until they shall have been 
amply confirmed. 

The researches of Pfliiger upon the salivary glands leave 
no doubt as to the fact that medullated nerve-fibres pass to 
the cells of these organs and there abruptly terminate, at 
least as dark-bordered fibres. This author believes, how- 
ever, that, having formed a more or less branching plexus, 
non-medullated fibres pass directly into the glandular cells, 
and he gives figures which seem to illustrate this arrange- 
ment pretty clearly. The same observer describes and fig- 
ures multipolar cells, mixed with the glandular cells, in 
which some of the nerve-fibres terminate. 1 

Modes of Termination of the Sensory Nerves. There 
are undoubtedly several modes of termination of the sensi- 
tive nerves in integument and mucous membranes, some of 
which have been accurately enough described, while others 
are still somewhat uncertain. In the first place, anatomists 
now recognize three varieties of corpuscular terminations, 
differing in their structure, probably, according to the differ- 
ent functions connected with sensation, with which the parts 
are endowed. In addition, it is probable that many sensi- 
tive nerves are connected with the hair-follicles, which are 
BO largely distributed throughout the cutaneous surface. 
There are, also, terminal filaments not connected with any 
special organs, some of them, perhaps, ending simply in free 
extremities, and some connected with epithelium. There is 
still considerable difference of opinion among anatomists 

1 PFLUGER, in STRICKER, Manual of Human and Comparative Histology, Lon- 
don, 1870, vol. i., p. 433, et seq. The views here advanced by Pfliiger have been 
confirmed by him in more recent observations and extended to the pancreas 
(Journal of Anatomy and Physiology, Cambridge and London, 1870, vol. iv., p. 
156). Pfliiger states, also, his belief that the same connection exists between the 
nerves and the liver-cells (ibid., p. 188). The question, however, is still some- 
what uncertain, and Mayer, in examinations of the salivary glands, found fila- 
ments in connection with the nuclei, but failed to satisfy himself that they were 
nervous (Quarterly Journal of Microscopical Science, London, April, 1870, p. 199) 



CORPUSCLES OF PACINI, OR OF VATEK. 37 

concerning all of these various points, but with regard to the 
terminal corpuscles, these differences are purely anatomical, 
and do not materially affect the physiology of sensation. 
"We do not propose, therefore, to enter fully into the discus- 
sions upon these questions, and will simply present what 
seem to be the most reasonable views of the latest and most 
reliable observers. 

Corpuscles of Pacing or of Vater. These corpuscles, 
which were the first discovered and described in connection 
with the sensitive nerves, were called corpuscles of Pacini, 
until it was shown that they had been seen about a century 
and a half ago by Yater. Their actual mode of connection 
with the nerves, however, has only been ascertained within 
the last few years. The following are the measurements of 
these bodies and the situations in which they are found, 
taken from Kolliker : 1 

In man, these corpuscles are oval or egg-shaped, and 
measure from ^j- to % of an inch in length. They are always 
found in the subcutaneous layer on the palms of the hands 
and the soles of the feet, and are most numerous on the 
palmar surfaces of the fingers and toes, particularly the third 
phalanges. In the entire hand there are about six hundred, 
and about the same on the feet. They are sometimes, but 
not constantly, found in the following situations : The dor- 
sal surfaces of the hands and feet ; on the cutaneous nerves 
of the arm, the forearm and the neck, the internal pudic 
nerve, the intercostal nerves, all of the articular nerves of 
the extremities, the nerves beneath the mammary glands, 
the nerves of the nipples, and in the substance of the 
muscles of the hands and feet. They are found without ex- 
ception on all of the great plexuses of the sympathetic sys- 
tem, in front of and by the sides of the abdominal aorta, and 
behind the peritoneum, particularly in the vicinity of the 

1 KOLLIKER, Elements d'histologie humaine, Paris, 1868, p. 141. 



38 



NERVOUS SYSTEM. 



pancreas. They sometimes exist in the mesentery, and have 

been observed near the coccygeal gland. 

The structure of the cor- 
puscles consists simply of sev- 
eral layers of connective tis- 
sue enclosing a central bulb 
in which is found the terminal 
extremity of .the nerve. This 
bulb is finely granular, nucle- 
ated, and is considered by most 
anatomists to be composed of 
connective tissue. At the base 
of the corpuscle is a pedicle 
formed of connective tissue sur- 
rounding a medullated nerve- 
fibre which penetrates the cor- 
puscle and terminates in the 
central bulb. 

The only really important 
point of discussion with refer- 
ence to the structure of the 
nerve-fibre in the central bulb, 
and this is purely anatomical, 
is whether or not the medul- 
lary substance extends into the 
corpuscle itself. Probably the 
fibre is here reduced simply 
to the axis-cylinder. Kolliker 
thinks that there is a very thin 
layer of medullary substance, 
but he states that this is a ques- 

and extremities of the fibre. ' (KOLLIKER, + ,. J'ffi T, j -i i i A n 
Handbuch der Gewelelehre Leinzi- 1S6T tlon CUmCUit tO deClCle. All 
8.108.) . . , . 1 

anatomists agree that a single 

thin, flat fibre penetrates the corpuscle and terminates near 

its summit in two or three branches, with slightly enlarged 

1 Op. tit., p. 143. 




TACTILE CORPUSCLES. 39 

and granular extremities. The arrangement of the different 
anatomical elements is shown in Fig. 4. 

The situation of these corpuscles beneath, instead of in 
the substance of the true skin, shows that they cannot be 
properly considered as tactile corpuscles, a name which is ap- 
plied to other structures situated in the papillae of the coriiim ; 
and it is impossible to assign to them any special function 
connected with sensation, such as the sense of temperature, 
or the appreciation of pressure or weight. All that we can 
say with regard to them is that they constitute one of the 
several modes of termination of the nerves of general sensi- 
bility. 

Tactile Corpuscles. The name tactile corpuscles implies 
that these bodies are connected with the sense of touch ; and 
this view is sustained by the fact that they are found almost 
exclusively in parts endowed to a marked degree with tac- 
tile sensibility. They are sometimes called the corpuscles of 
Meissner and Wagner, after the anatomists by whom they 
were first described. The most interesting researches into 
their structure, however, are of later date. The view ordi- 
narily accepted with regard to the structure of these bodies 
is that adopted by Kolliker, who has himself investigated 
their anatomy very closely ; but his researches have been 
controverted very strongly by Eouget. All are agreed con- 
cerning the situations where these corpuscles are found, their 
number, etc., the discussions with regard to their structure 
being confined to their mode of connection with the nerve- 
fibres. 

The true tactile corpuscles are found in greatest number 
on the palmar surfaces of the hands and fingers and the plan- 
tar surfaces of the feet and toes. They exist, also, in the 
skin on the backs of the hands and feet, the nipples, and a 
few on the anterior surface of the forearm. As we shall see 
when we come to describe them fully, they are situated in 
the substance of the papillae of the skin, and they cannot fail 



4:0 NERVOUS SYSTEM. 

to have an important function in connection with the sense 
of touch. 

"We have already treated of the structure of the skin in 
another volume, 1 where we have seen that the largest pa- 
pillae, measuring from ^ to -g-J-g- of an inch in length, are 
found on the hands, feet, and nipples, precisely where the 
tactile corpuscles are most abundant. Corpuscles do not 
exist in all papillae, and are found chiefly in those called com- 
pound. In the space of about -^ of an inch square on the 
third phalanx of the index-finger, Meissner counted four 
hundred papillae, in one hundred and eight of which he found 
tactile corpuscles, or about one in four. In the same space on 
the second phalanx, he found forty corpuscles ; on the first 
phalanx, fifteen ; eight on the skin of the hypothenar emi- 
nence ; thirty-four on the plantar surface of the ungual phalanx 
of the great-toe ; and seven or eight in the skin on the middle 
of the sole of the foot. In the skin of the forearm, the cor- 
puscles are very rare. 2 Kolliker states, also, that the tactile 
corpuscles usually occupy special papillae, which are not pro- 
vided with blood-vessels ; so that the papillae of the hand 
may be properly divided into vascular and nervous. 

The form of the tactile corpuscles is oblong, with their 
long diameter in the direction of the papillae. Their length 
is from -g-J-g- to -^-5- of an inch. In the palm of the hand, they 
are from -%^ to y-J-g- of an inch long, and from -g-g-^- to -g-j-g. of 
an inch in thickness. 3 They are generally situated at the 
summits of the secondary eminences of the compound pa- 
pillae. 

It is almost certain that the tactile corpuscles consist of 
connective-tissue elements, with nerve-fibres making a few 
spiral turns on their surface and finally disappearing in their 
substance. This view is most ably supported by Kolliker, in 
opposition to the proposition advanced by Eouget, that the 

1 See vol. iii., Excretion, p. 115. 

2 KOLLIKER, Elements d'histologie Jiumaine, Paris, 1868, p. 139. 

3 KOLLIKER, op. cit., p. 138. 




TACTILE CORPUSCLES. 41 

strise on the surface of the corpuscles are produced exclusively 
by nerve-fibres. According to Kolliker, the tactile corpuscles 
consist of a central bulb of homo- 

FIG. 5. 

geneous or slightly granular con- . ^ 

nective-tissue Substance, analo- 
gous to the central bulb of the 
Pacinian corpuscles, and a cov- 
ering. Treated with acetic acid, 
the covering presents numerous 
elongated nuclei arranged in a 
circular manner, which he be- 
lieves to be nuclei of connective 
tissue, and a few fine elastic fibres. 
One, two, and sometimes three 
or four dark-bordered nerve-fibres 

Cutaneous papilla. er, cortical layer with 

paSS from the SubcutaneOUS ner- plasmatic cells and fine elastic fibres ; 

&, tactile corpuscle, with transverse 

VOUS pleXUS tO the base Of each nuclei; c, afferent nervous branch, 

__.. with its nucleated neurilemma ; c?, 

COrpUSCle. liiese SUrrOUnd the nerve-fibres encircling the corpuscle: 

. e, the apparent termination of one of 

COrpUSCle With two Or three Spiral these fibres. (KOLLIKER, Hanflbnc.il 

der GewebeMire, Leipzig, 1S67, S. 106.) 

turns, and terminate by pale ex- 
tremities at the surface of the central bulb. 1 This arrange- 
ment is shown in Fip\ 5. 

O 

Rouget believes that the spiral lines on the surface of 
the corpuscles are produced exclusively by gelatinous, nu- 
cleated nerve-fibres which cover them completely, some- 
times dividing and sometimes remaining single, and that 
the fibres terminate in a nucleated central mass, entirely 
analogous to the nucleated expansion of the motor nerves. 
He claims to have demonstrated this in preparations 
treated for two or three days in a liquid containing one drop 
of acetic acid in about three and a third fluidounces of water, 
and afterward washed in pure water, which denudes the 
papillae of their epithelium. 2 In his endeavor to establish a 

1 KOLLIKER, op. cit., p. 138. 

2 ROUGET, Memoire sur les corpuscles nerveux qui se rencontrent d Vorigine des 
nerfs sensitifs, dans les papilles de la peau et des muqueuses, Archives de physi- 
ologie, Paris, 1868, tome i., p. 599. 



4:2 NERVOUS SYSTEM. 

complete analogy between the terminations of the sensitive 
and the motor nerve-fibres, Rouget does not seem to be en- 
tirely sustained ; for the behavior of the different anatomical 
elements of the tactile corpuscles when treated by acetic 
acid, and again when colored with carmine, shows conclu- 
sively the presence of connective-tissue elements in their 
outer covering. The observations of Kolliker and others 
leave no doubt upon this point ; l and as we have already 
seen in treating of the structure of the nerve-fibres, 2 the 
changes produced by acetic acid enable us to readily distin- 
guish the gelatinous nucleated fibres from the elements of 
connective tissue. While the exact mode of termination 
of the fibres in the tactile corpuscles is not perfectly clear, 
we must adopt for the present the views of Kolliker, as the 
most reasonable and satisfactory. 

Terminal I>ulbs. Under this name, a variety of cor- 
puscles has lately been described by Krause 3 as existing in 
the conjunctiva covering the eye and in the semilunar fold, 
the fioor of the buccal cavity, the tongue, the glans penis, 
and the clitoris. They bear some analogy to the tactile cor- 
puscles, but are much smaller and more simple in their struct- 
ure. They form simply a rounded or oblong enlargement 
at the ends of the nerves, which is composed of homogeneous 
matter with an exceedingly delicate investment of connec- 
tive tissue. They measure from 10 1 00 to -^fa of an inch in 
diameter. In the parts provided with papillae, they are situ- 
ated at the summits of the secondary elevations. 

The arrangement of the nerve-fibres in these corpuscles 
is very simple. One, two, or three medullated fibres pass 
from the submucous plexus to the corpuscles. The invest- 
ing sheath of the fibres is here continuous with the con- 
nective-tissue covering of the corpuscle, and the nerve- 

1 Loc. clt. 2 See page 26. 

8 W. KRAUSE, Die terminalen Korperchen der einfach sensibilen Nerven, Han- 
nover, 1860, S. 125, et sea. 



TERMINAL BULBG. 43 

fibres pass into the corpuscle, break up into two or three 
divisions, and terminate in convoluted or knotted coils. 



FIG. 6. 





B 

A. Three corpuscles of Krause from the conjunctiva of man, treated with acetic acid (magni- 
fied 300 diameters ) ; after a drawing by Ludden. 1, spherical corpuscle, with two nerve- 
fibres which form a knot in its interior. Portions of two pale nerve-fibres are also seen. 2, 
a rounded corpuscle presenting a nerve-fibre and fatty granulations in the internal bulb; 3, 
an elongated corpuscle with a distinct terminal fibre. In these three corpuscles, the covering, 
nucleated in 1 and 2, is distinguished. 

B. Terminal bulbs from the conjunctiva of the calf, treated with acetic acid (magnified 300 di- 
ameters) : after a drawing by Ludden. 1. extremity of a nerve-fibre with its bulb : '2, double 
bifurcation of a nerve-fibre, with two terminal bulbs : a. covering of the terminal bulbs : 6, 
internal bulb ; c, pale nerve-fibre. (KOLUKEE, Handbuch der Gewebelehre, Leipzig, 1867, 
S. 103.) 

The nerve-fibres are medullated for a certain distance, but 
their terminations are generally pale. The above is one 



44 NERVOUS SYSTEM. 

form of these corpuscles. Sometimes, however, the terminal 
bulbs are oblong, and sometimes but a single nerve-fibre 
penetrates the bulb and terminates in a simple pale filament. 
The principal forms of the terminal bulbs are shown in Fig. 6. 

General Mode of Termination of the Sensory Nerves. 
The actual termination of the sensitive nerves upon the gen- 
eral surface and in mucous membranes is still a question of 
great obscurity. Though we have arrived at a pretty defi- 
nite knowledge of the sensitive corpuscles, it must be t re- 
membered that there is an immense cutaneous and mucous 
surface in which no corpuscles have as yet been demon- 
strated ; and it is in these parts, endowed with what we may 
call general sensibility, as distinguished from the sense of 
touch, that we have to study the mode of termination of the 
nerves. 

Kolliker is of the opinion that, in the immense majority 
of instances, the sensitive nerves terminate in some way in 
the hair-follicles. 1 If this be true, it will account for the 
termination of the nerves in by far the greatest portion of 
the skin, as there are few parts in which hair-follicles do not 
exist ; but, unfortunately, the exact mode of connection of 
the nerves with these follicles is not apparent. The fol- 
lowing is all we know positively of the terminations of the 
nerves on the general surface : 

Medullated nerve-fibres form a plexus in the deeper lay- 
ers of the true skin, from which fibres, some pale and nucle- 
ated and others. medullated, pass to the hair-follicles, divide 
into branches, penetrate into their interior, and are there lost. 
A certain number of fibres pass to the non-striated muscu- 
lar fibres of the skin. A certain number pass to papillae and 
terminate in tactile corpuscles, and others pass to papillge 
that have no tactile corpuscles. 

In the mucous membranes, as far as we know, the mode 
of termination is, in general terms, by a delicate plexus just 

1 Op. dt., p. U4. 



STRUCTURE OF THE NERVE-CEXTRES. 45 

beneath the epithelium, coming from a submucous plexus 
analogous to the deep cutaneous plexus. In certain mem- 
branes, we have already noted the termination in bulbs (cor- 
puscles of Krause). In the cornea the fibres have been fol- 
lowed more minutely than in any other situation, and the 
results of recent researches on this subject are very remark- 
able. These results are so recent and unexpected, that we 
are hardly prepared to admit them unreservedly without 
fuller confirmation. At present we can only state that the 
observations of Hoyer, 1 Lipmann, 2 and others, confirmed in 
part by Kolliker, 8 seem to show that branching nerve-fibres 
pass to the nucleoli of the corpuscles of the cornea and to the 
nucleoli of the cells of the posterior layer of epithelium. 

Structure of the Neme-centres. 

A peculiar pigmentary matter in the nerve-cells and the 
surrounding granular substance gives to the nerve-centres 
a grayish color, by which they are readily distinguished 
from the white, or fibrous division of the nervous system. 
Wherever this gray matter is found, the anatomical ele- 
ments of the tissue are cellular, except in the nerves formed 
of gray, or gelatinous fibres. Under the general division of 
nerve-centres, we include, anatomically at least, the gray 
matter of the cerebro-spinal centres, the ganglia of the roots 
of the spinal and certain of the cranial nerves, and the nu- 
merous ganglia of the sympathetic system. In these parts 
are found cells, which constitute the essential anatomical 
element of the tissue, granular matter resembling the con- 
tents of the cells, pale fibres originating in prolongations of 
the cells, elements of connective tissue, delicate membranes 

1 HOYER, Ueber den Amtritt von Nervenfaser in das Epithel der Hornhaut. 
Archiv fur Anatomie, Physiologie und wissenschaftliche ATedicin, Leipzig, 1866, 
S. 180, et seq. 

2 LIPPMAXN, Ueber die Endigung den Nerven im eigentlichen Gewebe nnd im 
kinterea Epithel der Hornhaut des Frosches. ArchivfUr Pathologic, Anatomie und 
Physiologie, Berlin, 1869, Bd. xlviii., S. 218, et seq. 

3 KOLLIKER, fitments d'histologie humaine, Paris, 1868, p. 145. 



46 NERVOUS SYSTEM. 

enveloping some of the cells, and vessels. The most inter- 
esting and important of these structures, in their physiologi- 
cal relations, are the cells and the prolongations by which 
they are connected with the nerves. 

Nerve-cells. Anatomists are now pretty well agreed that 
the following varieties of cells exist in the nerve-centres, and 
constitute their essential anatomical elements ; viz., apolar, 
unipolar, bipolar, and multipolar cells. Although some have 
denied the existence of apolar cells, there can be little doubt 
of their presence in the centres in small numbers, and, as is 
suggested by Kolliker, they may be nerve-cells in an imper- 
fect state of development. The nerve-cells present great 
differences in their size and general appearance, and some 
distinct varieties are found in particular portions of the 
nervous system, and are probably connected with special 
functions. 

The apolar cells are simply rounded bodies, with granular 
contents, a nucleus and nucleolus like other cells, but with- 
out any prolongations connecting them with the nerve-fibres. 
They have been observed in the cerebro-spinal centres, and 
they always exist in the sympathetic ganglia. Those who 
deny their existence believe that the poles have been de- 
tached in preparing specimens for examination. Unipolar 
cells exist in some of the lower orders of animals, but their 
presence in the human subject is doubtful. Bipolar cells 
are found in the ganglia of the posterior roots of the spinal 
nerves, where they are of considerable size. Smaller bipolar 
cells are found in the sympathetic ganglia. Multipolar cells 
present three or more prolongations. 

Small cells, with three, and rarely four prolongations, 
are found in the posterior cornua of the gray matter of the 
spinal cord. From their situation they have been called 
sensitive cells. They are undoubtedly found in greatest 
number in parts known to be endowed exclusively with 
sensitive properties. 



NERVE-CELLS. 4:7 

Large, irregularly-shaped nmltipolar cells, with numer- 
ous prolongations, are found chiefly in the anterior cornua 
of the gray matter of the spinal cord, and have been called 
motor cells. These sometimes present as many as ten or 
twelve poles. . 

With all these differences in the size and form of the 
nerve-cells, they present tolerably uniform general charac- 
ters as regards their structure and contents. Leaving out 
the apolar and unipolar cells, the perfectly-developed cells 
are of an exceedingly irregular shape, with strongly-refract- 
ing, granular contents, frequently a considerable number of 
pigmentary granules, and a distinct nucleus and nucleolus. 
The nucleus in the adult is almost invariably single, though, 
in very rare instances; two have been observed. Cells with 
multiple nuclei are often observed in young animals. The 
nucleoli are usually single, but there may be as many as four 
or five. The strongly-refracting contents, the peculiar shape, 
and the poles or prolongations give the nerve-cells an ex- 
ceedingly characteristic appearance, which is represented in 
Fig. 7. ' 

The diameter of the cells is as variable as their form. 
They usually measure from I2 1 go to -g^-g- of an inch ; 1 but 
there are many of larger size, and some are smaller. The 
nuclei measure from 2 ^ 0() to I2 1 go of an inch. 

The nerve-cells are so delicate and prone to alteration 
that their study is exceedingly difficult. Sections of the 
nerve-centres must be prepared with great care, and are not 
easily made and preserved. In the numerous anatomical 
investigations that have been made within the last few years, 
the centres have generally been hardened artificially ; and 
almost every investigator has used different processes and 
reagents, which may account in a measure for the differ- 
ences of opinion that now exist on all points connected with 
the minute anatomy of these parts. 

There is at the present time considerable discussion with 

1 POUCHET, Precis d'histologie humaine, Paris, 1864, p. 139. 
104 



4:8 NERVOUS SYSTEM.- 

regard to the intimate structure of the substance of the nerve- 
cells, their nuclei and nucleoli, and the points involved have 
a certain amount of physiological interest. In the first place, 
the transverse striae in the axis-cylinder treated with nitrate 
of silver, noted by Frommann and confirmed by Grandly and 
others, have been observed by Grandry in the substance of 
the nerve-cells. 1 While this fact, perhaps, shows that the 



FIG. 7. 




Nerve-cell from the ferruginous substance which forms the floor of the rhomboidal sinus in man 
Magnified 850 diameters. (K6LLIKEB, Handbuch der Cfewefjelekre, Leipzig, Ib67, S. 291.) 

substance contained in the cells and their prolongations is 
the same as the substance of the axis-cylinder, as we stated 
with regard to the axis-cylinder, it is possible that the mark- 

1 See page 22. 



NERVE-CELLS. 49 

ings may be entirely artificial, and that they do not demon- 
strate the existence of two distinct substances in the tissue. 

The most interesting question with regard to the struct- 
ure of the nerve-cells relates to the mode of origin of their 
fibres, or poles. Until quite recently these have been re- 
garded as simple prolongations of the substance of the 
cells ; but lately the view has been advanced that the nerve- 
cells, in the human subject, are composed of regular fibrils 
continuous with the poles and starting, as it were, from 
the nucleoli. 1 The fibrillation of the nerve-cells and their 
prolongations is figured by Schultze in an article in one 
of the most authoritative of the recent works on histolo- 
gy ; a but some other eminent observers have failed to note 
the appearances here described, 8 at least in the human sub- 
ject and the mammalia. "With our , present knowledge of 
the physiology of the nerve-cells, the question whether or 
not their substance be fibrillated has little more than an ana- 
tomical interest ; but there can be no doubt that the cells of 
some of the lower orders of animals possess striations more 
or less regular. These, indeed, were described soon after the 
cells were discovered. While there is no anatomist who de- 
nies the fact that the substance of the cells is marked by 
stride in many animals, the existence of an analogous ar- 
rangement in the human subject is still doubtful. Some 
anatomists, with Schultze, admit the striations, but have 
foiled to connect them with the nuclei and nucleoli. All 
admit that they are demonstrated with great difficulty; and, 

1 BEALE, Indications of the Paths taken by the Nerve-currents as they traverse 
the caudate Nerve-cells of the Spinal Cord and Encephalon. Proceedings of the 
Royal Society, London, 1864, vol. xiii., p. 386, et seq. 

FROMMAXX, Ueber die Farbung der Binde- und Nervensubstanz des 

Ruckenmarkes durch Argentum nitricum und uber die Struktur der Nervenzellen. 
Archiv fur pathologische Anatomic und Physiologic, Berlin, 1864, Bd. xxxi., S. 
134. 

2 SCHULTZE, in STRICKER, Manual of Human and Comparative Histology, Lon- 
don, 1870, vol. i., p. 179. 

KOLLIKZR, Elements d'histologie humaine, Paris, 1868, p. 332. 



50 NERVOUS SYSTEM. 

while this question is so important that it can hardly be neg- 
lected in studying the physiological anatomy of the nerve- 
centres, it is one concerning which it seems impossible to ex- 
press a positive and definite opinion. 

Connection of the Nerve-cells with the Fibres and with 
each other. Although the mode of connection of the nerve- 
cells with the fibres and with each other is one of the most 
important, in its physiological bearings, of all the points 
connected with the minute anatomy of the nerve-centres, it 
is impossible, in the present state of our anatomical knowl- 
edge, to answer the questions involved in a manner entirely 
satisfactory. This statement is made after a thorough study 
of the investigations of the most reliable modern observers, 
among whom may be mentioned Stilling, Lockhart Clarke, 
Kolliker, K. "Wagner, Jacubowitsch, Yan der Kolk, Deiters, 
J. Dean, and Schultze, as the most prominent, with many 
others who have investigated the subject more or less success- 
fully. 1 A full discussion of the different opinions and the 
methods of investigation that have been employed would be 
out of place in this work. The difficulties in the way of 
arriving at positive information upon these questions are the 
following : 

1. The nerve-cells and their prolongations are so delicate 
and easily torn that they cannot be isolated and followed for 
any considerable distance, and theoretical considerations are 
constantly required to fill up the deficiencies in actual obser- 
vation. 

2. In the study of sections of the nerve-centres, the parts 
must be hardened and afterward rendered transparent by 
reagents, which must produce more or less change in the 
structures ; and it seems an anatomical impossibility to make 
tfrese sections so as to follow out the prolongations of the 

1 Kolliker gives a very full bibliography of the anatomy of the nervous- sys- 
tem, to which the reader is referred for more extended information. (Elements 
d'histologie humaine, Paris, 1868, p. 441.) 



CONNECTION OF NERVE-CELLS WITH FIBRES. 51 

cells far enough to establish beyond doubt their exact rela- 
tions. 

These two considerations alone are sufficient to account 
for the uncertainty so apparent even in the most successful 
investigations into the anatomy of the central nervous sys- 
tem ; and we shall content ourselves, in view of these facts, 
with giving a summary of what seems to be the probable 
relation of the cells to the fibres of origin of the nerves and 
to each other. 

Apolar cells, if they exist at all and be not cells from 
which the poles have become separated, are simple, rounded 
bodies, lying between the fibres, with which they have no 
other relation than that of mere contiguity. Unipolar cells 
have but one prolongation, which is continuous with a 
nerve-fibre. It is not certain that these exist in the human 
subject. 

Bipolar cells are found in the ganglia of the posterior 
roots of the spinal nerves and some of the sympathetic gan- 
glia. In many of the lower animals, particularly in fishes, 
the cells of the ganglia of the spinal nerves are simple, nucle- 
ated enlargements in the course of the sensitive nerve-fibres, 
and many anatomists have inferred that the same arrange- 
ment exists in man and the mammalia ; x but the constitution 
of these ganglia in the higher classes of animals seems to be 
entirely different. In the first place, the roots of the spinal 
nerves at the ganglia are undoubtedly reenforced by the ad- 
dition of new fibres, as Kolliker has shown by actual meas- 
urement, the roots being sensibly larger beyond the ganglia 
while the filaments of entrance and exit have the same diam- 
eter. 3 Direct observation upon the ganglia in man also fails 
to show the arrangement so clearly demonstrable in fishes. 
The cells in the posterior roots are not continuous with the 
fibres passing from the periphery to the cord, but give origin 
to new fibres, generally two in number, which sometimes are* 

1 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 95. 
* KOLLIKER, Elements d'histologie humaine, Paris, 1868, p. 419. 



52 NEBVOUS SYSTEM. 

single and sometimes bifurcated, and which pass, in by far 
the greatest number if not in all instances, to the periphery. 

The multipolar cells, with three or more prolongations, 
are found in all of the ganglia, but they predominate largely 
in the gray matter of the cerebro-spinal centres. It is the 
question of the exact mode of connection between these cells 
and the fibres of origin of the cerebro-spinal nerves and the 
union of the cells with each other by commissural prolonga- 
tions, that presents the greatest difficulty and uncertainty. 
One point, which has been raised within a few years, is with 
regard to the character of the different poles connected with 
the same cell. In ordinary preparations of the central ner- 
vous system, it is impossible, even with the highest available 
magnifying powers, to distinguish any one pole which, in its 
general characters and connections, is different from the 
others ; yet, some of the anatomists to whose researches we 
have alluded describe a single pole, more distinct in its out- 
lines than the others, which does not branch and is to be re- 
garded as an axis-cylinder. The other poles are supposed to 
be of a different character, not connected with the nerve- 
fibres, and always presenting a greater or less number of 
branches. These views are accepted by Schultze, who gives a 
figure, after Deiters, in which the contrast between the poles 
is represented as very marked ; 1 but although this opinion 
is accepted by other high authorities, 8 it is not easy to un- 
derstand how it can be received without reserve, when it 
is 'so difficult, if not impossible, to follow out the poles, ex- 
cept for a very short distance. 

"With our present means of investigation, there seems to 
be no doubt with regard to the following facts : Tracing 
the nerve-fibres toward their origin, they are seen to lose 
their investing membrane as soon as they pass into the 
white portion of the centres, being here composed only 

1 STRICKER, Manual of Human and Comparative Histology, London, 1870, 
vol. i., p. 1T7. 

2 KOLLIKER, fitiments (Phistologie humaine, Paris, 1868, p. 362 



ACCESSORY ELEMENTS LN" THE NERVE-CENTRES. 53 

of the medullary substance surrounding the axis-cylinder. 
They then penetrate the gray substance, in the form of axis- 
cylinders, losing here the medullary substance. In the gray 
substance, it is impossible to make out of all their relations 
distinctly, and we cannot assume, as a matter of positive dem- 
onstration, that all of them are connected with the poles of 
the nerve-cells. Still, it has been shown, in the gray matter 
of the spinal cord, that many of the fibres are actual prolon- 
gations of the cells, the others probably passing upward to 
be connected with cells in the encephalon. 

Tracing the prolongations from the cells, we find that 
one or more of the poles branch and subdivide in the gray 
substance, and give origin to fibres, but that these fibres do 
not branch after they pass into the white substance. Other 
poles connect the nerve-cells with each other by commissural 
fibres of greater or less length ; but it has never been posi- 
tively demonstrated that the cells are thus connected into 
separate and distinct groups, though this is possible. 

The accompanying figure, taken from the excellent mono- 
graph on the lumbar enlargement of the spinal cord, by Dean, 
shows the mode of connection between certain of the cellular 
prolongations and the fibres of the anterior roots, and the 
commissural fibres by which the cells are connected with each 
other. 

Accessory Anatomical Elements in the Nerve-centres. 
While we must regard the cells of the gray matter and the 
axis-cylinder of the nerves as probably the only anatomical 
elements concerned in innervation, there are other struct- 
ures in the nervous system which it is important for us to 
study. These are : 1, outer coverings surrounding some of 
the cells ; 2, intercellular, granular matter ; 3, peculiar cor- 
puscles, called myelocytes ; 4, connective-tissue elements ; 
5, blood-vessels and lymphatics. 

Certain of the cells in the spinal ganglia and the ganglia 
of the sympathetic system are surrounded with a nucleated 




Group of cells connected with the anterior roots, as seen in a transverse section, from the an- 
terior cornu of the sheep. A, entrance of the anterior roots into the cornu; 6, &, &, &, cells 
connected by long, slender processes, with the anterior roots ; c, boundary of the cornu. In 
this figure almost every variety of cell-connection may be seen, with bundles of fibres cross- 
ing in every direction. (DEAN, Microscopic Anatomy of the Lumbar Enlargement of the 
Spinal Cord, Cambridge, 1861, Fig. 4.) 



ACCESSORY ELEMENTS IN THE NERVE-CENTEES. 55 

covering, some distance removed from the cell itself so as to 
oe nearly twice the diameter of the cell, which is continuous 
with the sheath of the dark-bordered fibres. 1 This mem- 
brane is always nucleated, and Kolliker has lately shown 
hat it is not homogeneous, as was at one time supposed, but 
is composed of a layer of very delicate epithelium. 8 The 
physiological significance of this covering is not apparent. 

In the gray matter of the nerve-centres, there is a, finely- 
granular substance between the cells, which closely resem- 
bles the granular contents of the cells themselves. In addi- 
tion to this granular matter, Robin has described new ana- 
tomical elements which he has called myelocytes. These 
are found in the cerebro-spinal centres, forming a layer near 
the boundary of the white substance, and are particularly 
abundant in the cerebellum. They exist in the form of free 
nuclei and nucleated cells, the free nuclei being by far 
the more numerous. The nuclei are rounded or ovoid, with 
strongly-accentuated borders, are unaffected by acetic acid, 
finely granular, and generally -without nucleoli. The cells 
are rounded or slightly polyhedric, pale, clear, or very slightly 
granular, and contain bodies similar to the free nuclei. The 
free nuclei are from S J- OQ to -^m of an inch in diameter, and 
the cells measure from -g-gVo to 2 0*0 o ? and sometimes 14 1 00 of 
an inch.* These elements also exist in the second layer of 
the retina. 

There has been a great deal of discussion with regard to 
the presence or absence of connective-tissue elements in the 
cerebro-spinal centres. In the other ganglia, there has never 
been any doubt with regard to the presence of connective 
tissue in greater or less amount, and in the cerebro-spinal 
centres there can hardly be any question of the existence of 
an exceedingly delicate stroma, chiefly in the form of stel- 

1 SCHULTZE, in STRICKER, Manual of Human and Comparative Histology, 
London, 1870, vol. i., p. 173, el seq. 

2 KOLLIKER, Elements d'histologie humaine, Paris, 1868, p. 329. 

8 LITTRE ET ROBIN, Diclionnaire de medecine, Paris, 1865, Article, Myelocytts. 



56 NERVOUS SYSTEM. 

late, branching cells, serving, in a measure, to support the 
nervous elements. 

The blood-vessels of the nerve-centres form an exceed- 
ingly graceful capillary net-work with very large meshes. 
The gray substance is much richer in capillaries than the 
white. 

A remarkable peculiarity of the vascular arrangement in 
the cerebro-spinal centres has already been described in con- 
nection with the lymphatic system. The blood-vessels here 
are surrounded by what have been called peri vascular canals, 
first described by Robin, and afterward shown by His and 
Robin to be radicles of the lymphatic system. 1 

Composition of the Nervous Substance. 

Our knowledge of the chemical constitution of the ner- 
vous system is, in many regards, quite unsatisfactory ; but 
these tissues contain certain elements that have been very 
well determined. The chemical characters of cholesterine, 
for example, have long been known to physiologists, as well 
as the fact that this principle is a constant constituent of the 
nervous substance, united in some way with the other proxi- 
mate principles, so that it does not appear in a crystalline 
form. Since we demonstrated, in 1862, the relations of 
cholesterine to the process of disassimilation, this principle 
has assumed its proper place as one of the most important 
of the products of physiological waste of the organism. The 
origin and function of cholesterine, with the processes for its 
extraction from the fluids and tissues of the body, have been 
fully considered under the head of excretion. 3 

Regarding cholesterine as an excrementitious product, 
to be classed with principles destined simply to be elimi- 
nated from the organism, the nerve-substance proper has 
been found to contain the following proximate principles, 
the chemical properties of which have been more or less 

1 See vol. ii., Absorption, p. 433. 2 See vol. iii., Excretion, p. 267, et seq. 



PBOTAGON. 57 

accurately determined ; viz., protagon, neurine, fatty matters 
combined with phosphorus, and bases combined with peculiar 
fatty acids. 

Protagon. This principle was discovered by Liebreich, 
and described in 1865. 1 Its formula is C 116 H 341 O 3a ]Sr 4 P. It 
may be extracted by the following process : The cerebral 
substance is bruised in a mortar, and afterward shaken with 
water and ether in a closed vessel. The mixture is then ex- 
posed to a temperature of 32 Fahr., and the ethereal layer, 
containing cholesterine, is removed. The insoluble mass is 
then extracted with alcohol, 85 per cent., at 113, is again 
filtered and exposed to a temperature of 32. An abundant 
precipitate then separates, which is washed with ether and 
desiccated in vacuo. The protagon is thus obtained in the 
form of a white powder. Since this principle has been de- 
scribed in the brain-substance, a compound analogous to, if 
not identical with protagon, has been discovered by Her- 
mann in the blood-corpuscles. 5 In its general and chemical 
characters, protagon resembles the albuminoid proximate 
principles ; but it presents the remarkable difference, that 
the sulphur, which exists in many of the principles of this 
class, is replaced by phosphorus. 



. This name has been applied to a rather indefi- 
nite principle supposed to represent the albuminoid element 
of the nervous tissue ; but its characters as a proximate con- 
stituent of the nerve-substance have never been well deter- 
mined. Robin and Yerdeil place neurine among the proxi- 
mate principles of probable existence. According to these 
authors, this is the organic substance of the brain, not soluble 

1 LIEBREICH, Ueber die chemische Beschaffenheit der Gehimsiibstanz. Annalen 
der Chemie und Pharmacie, Leipzig und Heidelberg, 1865, Bd. cxxxiv., S. 29, 
(t seq. 

8 HERMANN*, Ueber das Vorlcommen von Protagon im Blute. Archiv fur 
pathologische Anatomic und Physiologic, Berlin, 1866, S. 36, ft seq. 



58 NERVOUS SYSTEM. 

in alcohol. When incinerated it does not leave a residue 
impregnated with phosphoric acid, like the cerebral fatty 
matter. 1 According to more recent investigations, particu- 
larly those of Liebreich, neurine is a derivative of protagon. 
The neurine of Liebreich is obtained by boiling protagon for 
twenty-four hours in baryta-water, when there is formed the 
phospho-glycerate of baryta, and a new base, neurine. 8 It is 
evident that this substance cannot properly be regarded as a 
well-determined proximate principle. 

"We have already alluded to the experiments of Wurtz 
upon the synthesis of neurine. 3 These observations are im- 
portant as a step toward the synthesis of organic nitrogen- 
ized principles, but they do not afford an example of the 
actual formation of a characteristic nitrogenized constituent 
of the nerve-tissue. They simply show that the chlorohy- 
drate of an artificial organic compound presents crystals 
identical with the chlorohydrate of neurine extracted from 
the brain. 4 

Cerebral Fatty Principles. Researches into the compo- 
sition of the fatty principles found in the nervous substance 
have been so indefinite and unsatisfactory in their results, 
that even now they possess but little physiological interest. 
In the earlier observations, the fats extracted from the nerve- 
tissue were generally combined with cholesterine. This sub- 
stance has now been isolated, and the residue contains a 
variety of principles, which seem, under physiological condi- 

1 KOBIN ET VERDEIL, Traite de chimie anatomique, Paris, 1853, tome iii., 
p. 451. 

2 LIEBREICH, loc. cit. ; and, Journal de Vanatomie, Paris, 1866, tome iii., p. 654. 

3 See vol. iii., Excretion, p. 195, foot-note. 

4 WURTZ, Sur Vldentite de la nevrine artifiddle avec la nevrine naturdle. 
Comptes rendus, Paris, 1868, tome Ixvi., p. 772, et seq. Wurtz obtained neurine 
by the reaction of trymethylamine upon monochlorohydric glycol. He found 
that the chlorohydrate of trymethyloxethylammonium was identical with the 
chlorohydrate of neurine prepared with neurine from the brain. By neurine, 
Wurtz undoubtedly means the principle described under that name by Liebreich. 



COBPOBA AMYLACEA. 59 

tions, to be intimately united with the nitrogenized substance, 
presenting one of the exceptions to the general law that fats 
exist in the body, uncombined, except with each other. In 
tliis mass of fatty matter, we can determine the presence of 
oleine, margarine, and stearine ; but these are combined with 
other fats, fatty acids, etc., the remarkable peculiarity of most 
of which is, that they contain a certain proportion of phos- 
phorus. These peculiar principles have received a variety 
of names, as they have been described more or less minutely 
by different observers, such as cerebrine, white and red 
phosphorized fat, lecithene, cerebric acid, and cerebrate of 
soda. The application of most of these names is very indefi- 
nite, and when we say that the substances are, in greatest 
part, peculiar to the nervous tissue, and that they contain 
phosphorus, we have stated about all that is physiologically 
important. Lecithene is a neutral phosphorized fat, proba- 
bly composed of a number of different fatty principles, which 
exists, not only in the nervous substance, but in the blood, 
bile, 1 and the yolk of egg. 3 Its chemical history has no 
physiological interest. The same may be said of cerebric 
acid, the cerebrate of soda, oleo-phosphoric acid and its com- 
pounds with soda and lime. 

Corpora Amylacea. Little rounded or ovoid bodies, about 
j-sVcr of an inch in diameter, have been described by Yir- 
chow and others 3 as existing normally in the corpora stria ta, 
the medulla oblongata, and some other portions of the 
cerebro-spinal system. With regard to the actual compo- 
sition of these bodies, there is considerable difference of 
opinion. Yirchow and many others regard them as identi- 
cal with starch, the granules of which they certainly resemble 
very closely, being of the same shape, with borders well 

1 See voL iii., Excretion, p. 262. 

8 LITTRE ET ROBIN, Dictionnaire de medecine, Paris, 1865, Article, Lecithene. 
8 VIRCHOW, Cellular Pathology, Philadelphia, 1863, p. 320. 
, Human Physiology, Philadelphia, 1867, p. 66. 



60 NERVOUS SYSTEM. 

defined, frequently presenting concentric laminae and a hilum. 
When carefully treated, first with a solution of iodine and then 
with a little sulphuric acid, they assume a blue color. Some 
observers consider them as analogous to cellulose, others have 
supposed that they are formed of cholesterine, and others 
regard them as nitrogenized bodies. * These points are of 
purely anatomical interest, and the physiological relations 
of these bodies are not known. 

Regeneration of the Nervous Tissue. 

"We do not propose to discuss fully the question of the 
regeneration of nerves after section or even excision of a 
portion of their substance, though it is one of great patho- 
logical interest ; but in this connection will refer to some 
experiments recently made, in which it appears that it is pos- 
sible for certain of the most important of the nerve-centres 
to be regenerated and their function restored after extir- 
pation. 

"With regard to the simple reunion of nerves after division 
or excision, it has long been known that this takes place in 
the human subject and in the inferior animals, with restora- 
tion of function. 3 The new tissue connecting the divided 
extremities of the nerve seems to pass through the regular 
stages of development observed in the nerve-tissue of the 
embryon, the gelatinous fibres, or the fibres of Remak, first 
appearing, and these being subsequently developed into true 
nerve-tubes. In this process there is not a cicatrix, as in 
the skin or muscular tissue, but a development of new ele- 
ments possessing the anatomical and physiological charac- 
ters of the original structure. 

1 VIRCHOW, he. tit. 

LITTRK ET ROBIN, Dictionnaire de medecine, Paris, 1865, Article, Cor- 
puscle. 

2 LAVERAN, Recherches experimentales sur la regeneration des nerfs, These, 
Strasbourg, 1867. This memoir contains an elaborate review of the earlier ex- 
periments upon the regeneration of nerves, with some original observations of 
much interest. 



REGENERATION OF THE NERVOUS TISSUE. 61 

The fact of the speedy and complete reunion of divided 
nerves has been taken advantage of by physiologists in 
experiments upon nerves of different functions. Many years 
ago, Flourens divided two mixed nerves, the trunks of which 
were near each other, and crossed them, connecting the central 
end of the one with the peripheral end of the other, and vice 
versa. Reunion of the extremities thus attached took place, 
and the functions of the paralyzed parts were restored. The 
communication through both nerves was restored and corre- 
sponded to the artificial crossing of the nerves. In these 
experiments there was complete reunion of the extremities 
of different nerves possessing the same general properties. 
Flourens then attempted to produce, in the same way, an 
anatomical and physiological reunion between the divided 
extremities of nerves of different properties, as the pneumo- 
gastric and the fifth cervical. At the end of three months 
the anatomical reunion was found complete ; but on dividing 
the other pneumogastric, to ascertain if the function of the 
first had been restored, the animal manifested the symptoms 
that follow division of both pneumogastrics, and died in two 
days. 1 These experiments have lately been repeated and 
extended by Gluge and Thiernesse, 8 Philipeaux and Yul- 
pian, 3 and others, with more definite results. Gluge and 
Thiernesse, Schiff, 4 and Landry 6 failed to observe restoration 

1 FLOURENS, Recherches experimentales sur les proprietes et les functions du 
gysteme nerveux, Paris, 1842, p. 266, et seg. 

2 GLUGE ET THIERNESSE, JSur la reunion des fibres nerveuses sensibles avec les 
fibres matrices. Journal de la physiologic, Paris, 1859, tome ii., p. 686, et seq. 

3 PHILIPEAUX ET VULPIAN, Note sur des experiences demontrant que des nerfs 
separes des centres nerveux peuvent, apres s^etre alteres completement, se regenerer 
tout en demeurant isolts de ces centres, et recouvrer leurs proprietis physiologiques. 
Journal de la physiologie, Paris, 1860, tome Hi., p. 214 ; Recherches experimen- 
talessur la reunion bout d boutde nerfs defonctions different^. Ibid., 1863, tome 
vi., p. 421, et seq., and p. 474, et seq. 

4 SCHIFF, Remarques sur les experiences de MM. Philipeaux el Vulpian sur la 
regeneration des nerfs. Journal de la physiologic, Paris, 1860, tome iii., p. 217. 

5 LANDRY, Reflexions sur les experiences de MM. Philipeaux et Vulpian, rela- 
tives d la regeneration des nerfs. Ibid., p. 218. 



62 NEKVOUS SYSTEM. 

of the function of nerves of different properties that became 
reunited after division. The experiments upon this point 
by Gluge and Thiernesse were the most extended, and were 
made upon the lingual branch of the fifth pair and the sub- 
lingual. In from three to six weeks, the central end of the 
sensitive nerve became firmly united with the peripheral end 
of the motor nerve, but the physiological union was in no 
case observed, except in one experiment in which the central 
end of the sublingual was involved in the reunion. 1 This 
conclusion was arrived at after a failure to obtain move- 
ments in the tongue by stimulating the lingual branch of the 
fifth above the point of union. 

It is evident that these experiments must have an impor- 
tant bearing upon our theories concerning the mode of con- 
duction of motor stimulus and sensitive impressions by the 
different nerves, and they will be referred to again in con- 
nection with that part of our subject. At present we can 
only refer to the positive results obtained by Philipeaux and 
Yulpian, which are in opposition to the negative experi- 
ments of the observers cited above. These physiologists 
succeeded in uniting, in dogs, the central end of the pneumo- 
gastric with the peripheral end of the sublingual, and the 
central end of the lingual branch of the fifth with the periph- 
eral end of the sublingual, all of the nerves being divided, 
and, in the case of the sublingual and the lingual branch of 
the fifth, the central end of the motor nerve being torn out. 
In these experiments, on exposing the nerves four or five 
months after the first operation, irritation applied to the 
sublingual below the point of union produced pain, and a 
stimulus applied to the lingual branch of the fifth above the 
point of union excited movements of the tongue, even after 
dividing the nerve above and separating it from the centres, 
so that it was impossible for any reflex movements to take 
place. 8 These facts show that not only does union take 

1 GLUGE ET THIERNESSE, he. tit., p. 695. 

2 See the memoirs by PHILIPEAUX AND VULPIAN, already cited from the 



REUNION OF NERVES OF DIFFERENT PROPERTIES. 63 

place in nerves after division, and between the divided ex- 
tremities of two different nerves having the same properties, 
but that the divided extremity of a motor nerve may be made 
to form an anatomical and physiological union with the 
divided extremity of a nerve of sensation, and that both 
motor and sensitive currents may be conducted through the 
fibres at the point of union. 

The only remaining point of physiological interest con- 
nected with the regeneration of the nervous tissue is in- 
volved in the recent observations of Yoit on the regeneration 
of the cerebral lobes after removal in a pigeon, and those of 
Masius and Yanlair upon the anatomical and functional re- 
generation of the spinal cord in frogs. 

The experiments recorded by Voit, and his deductions, 
are very curious, and have given rise to a great deal of com- 
ment and criticism. In one observation, the cerebral lobes 
were removed from a young pigeon in the usual way, an 
operation very easily performed, and one which we practise 
yearly as a class-demonstration. It is particularly stated that 
the operation was complete, and that the entire posterior 
lobes were removed. Immediately after the operation, the 
pigeon presented the condition of stupor ordinarily observed. 
As he gradually recovered from this condition, he . began to 
execute a number of mechanical movements, which it is un- 
necessary to detail fully, in the most extraordinary manner. 
The animal continued to improve, ceased the mechanical 
movements, and began to fly about, exhibiting timidity when 
approached, and, in short, seemed, after a time, to have quite 
or nearly returned to the normal condition. One thing, 
however, was remarked : the animal never took food (it was 
probably kept alive by stuffing, as is frequently done in such 
experiments). After five months, the pigeon was killed. 
The cranial cavity was found to be filled with a white mass, 
occupying the place from which the cerebrum had been re- 

J&urnal de la physiologie ; and, VULPIAN, Lemons sur la physiologic generale et 
comparee du systeme nerveux, Paris, 1866, p. 280, et seq. 
105 



64 NERVOUS SYSTEM. 

moved. This mass had the consistence of the white substance 
of the brain, and presented a perfect continuity with the 
cerebral peduncles, which had not been removed. It had 
the form of the two hemispheres, presenting a cavity filled 
with liquid and a septum. The whole mass consisted of per- 
fect primitive fibres of double contour, and, in their meshes, 
ganglionic cells. 1 

This observation is certainly one of the most remarkable 
on record, and, from the extraordinary character of its 
results, would hardly be accepted for a moment, but for the 
established reputation of Prof. Voit. As it is, such an ob- 
servation demands full confirmation. It is well known to all 
who have been in the habit of removing the cerebral lobes, 
that it is absolutely necessary to remove every portion of 
their substance, in order to obtain uniform results, and that 
this is accomplished sometimes with considerable difficulty. 
In demonstrations to a medical class, we have frequently 
verified this fact, and have observed recovery, more or less 
complete, when but a small portion of the posterior lobes 
escaped. This criticism upon the remarkable observation 
just detailed is made by Yulpian, 2 and its pertinence will be 
recognized by every practical physiologist. "We have only 
to study the experiments first made by Flourens, to learn 
how, in the lower animals, a part of one of the great central 
ganglia may gradually assume the function of the whole, after 
this function has been interrupted by the first mutilation. 3 

"We have cited the essential points in this observation 
because it has been so extensively commented upon by 
physiologists, but it is far from establishing the principle 
that a great nervous centre, like the cerebrum, may be ana- 
tomically and functionally regenerated after extirpation. 

1 C. VOIT, Phenomenes qui suivent Vdblation des hemispheres du cerveau cJiez 
les pigeons (Academic des Sciences de Munich], traduit de T allemand par le Dr. 
RABUTEAU. Revue des cours scientifiques, Paris, 1869, tome vi., p. 256. 

2 VULPIAN, Archives de physiologic, Paris, 1869, tome ii., p. 802. 

3 FLOURENS, Recherches experimentales sur les proprietesel lesfonclions du sys- 
teme nerveux, Paris, 1842, p. 100. 



REGENERATION OF NERVOUS TISSUE. 65 

The general results of the experiments of Masius and 
Yanlair upon the regeneration of parts of the spinal cord 
in frogs, after loss of a small portion of its substance, show 
that such reparation may take place and is attended with 
restoration of function. The formation of cells precedes the 
development of fibres, and voluntary motion appears in the 
parts situated below the lesion, before sensation. 1 There are 
no instances on record of such regeneration in the human 
subject or in the warm-blooded animals. 

1 MASIUS ET YANLAIR, Recherches ezperimentoles sur la regeneration anato- 
migue et fonctionnelle de la moelle epinere, Bruxelles, 1870. 



CHAPTEE H. 

MOTOR AND SENSORY NERVES. 

Distinct seat of the motor and sensory properties of the spinal nerves Specu- 
lations of Alexander Walker Views of Sir Charles Bell regarding the func- 
tions of the anterior and posterior roots of the spinal nerves Experiments 
of Magendie on the roots of the spinal nerves Properties of the posterior 
roots of the spinal nerves Influence of the ganglia upon the nutrition of 
the posterior roots Properties of the anterior roots of the spinal nerves 
Recurrent sensibility Mode of action of the motor nerves Associated 
movements Mode of action of the sensory nerves Sensation in amputated 
members. 

THE physiological property of nerves which enables them 
to conduct to and from the centres the impressions, stimulus, 
force, or whatever the imponderable nervous agent may be, 
is one inherent in the tissue itself, belonging to no other 
structure, and is dependent for its continuance upon proper 
conditions of nutrition. So long as the nerves maintain these 
conditions, they retain this characteristic physiological prop- 
erty, which is generally known under the name of irritability. 

Aside from the special senses, the sense of temperature, 
and of weight, it is known to every one that through the 
nerves we appreciate what are called ordinary sensations, 
and are enabled to execute voluntary movements. If a 
nerve distributed to a part endowed with sensation and the 
power of motion be divided, both of these properties are 
lost, and can only be regained through a reunion of the di- 
vided nerve. Again, it is equally well known that if such 
a nerve be exposed in its course and irritated, violent move- 
ments take place in the muscles to which it is distributed, 
and pain is appreciated, referred to parts supplied from the 



MOTOR AND SENSORY NERVES. 67 

same source. These facts, which were fully appreciated by 
the ancients, show that the general system of nerves is 
endowed with motor and sensory properties, the question 
being simply whether these be inherent in the same fibres 
or belong to fibres physiologically distinct and derived from 
different parts of the central system. This question, which 
was solved only about half a century ago, will be the first 
to engage our attention. 

Distinct Seat of the Motor and Sensory Properties of the 
Spinal Nerves. All of the nerves that take their origin 
from the spinal cord are endowed with motor and sensory 
properties. These nerves supply the whole body, except 
the head and other parts receiving branches from the cranial 
nerves. They arise by thirty-one pairs from the sides of the 
spinal cord, and each nerve has an anterior and a posterior 
root. The anatomical differences between the two roots are 
that the anterior is the smaller, and ha"s no ganglion. ' The 
larger, posterior root presents a ganglionic enlargement in the 
intervertebral foramen. Just beyond the ganglion, the two 
roots coalesce and form a single trunk. The nerve-fibres in 
the two roots are not of the same size, the anterior fibres 
measuring on an average about one-fourth more than the 
posterior fibres. 1 The structure of the ganglia of the poste- 
rior roots has already been considered sufficiently in detail. 3 

It would be unprofitable to discuss the vague ideas of the 
older anatomists and physiologists with regard to the proper- 
ties of the roots of the spinal nerves, and we can date our in- 
formation upon this point from the suggestion of Alexander 
Walker, in 1809, that one of these roots was for sensation 
alone and the other for motion. 3 It is most remarkable, 
however, that "Walker, from purely theoretical considera- 

1 KOLLIKER, Elements d'histologie humaine, Paris, 1868, p. 339. 

2 See page 51. 

3 WALKER, New Anatomy and Physiology of the Brain in particular and of 
the Nervous System in general Archives of Universal Science, Edinburgh, 1809, 
vol. iii., pp. 173, 174. 



68 NEKVOUS SYSTEM. 

tions, should have stated that the posterior roots were motor 
and the anterior roots sensory, precisely the reverse of the 
truth, and should have advanced this view in a publication 
as late as 1844. 1 In the work alluded to, which contains 
some of the most extraordinary pseudo-scientific vagaries 
ever published, it is curious to see how near Walker came to 
the greatest discovery in physiology since the description of 
the circulation of the blood. He gives an account of an ex- 
periment as follows : " On opening the spinal canal of a 
frog, accordingly, and performing the only operation on a 
living animal which he ever has performed, or ever will per- 
form, he found that, in perfect conformity with previous 
reasoning, irritation of the anterior roots caused motion, 
and irritation of the posterior roots caused little or none." ' 
!N~ow, it does not appear in the work from which this quota- 
tion is made at what time this experiment was performed ; 
and we have not been able to ascertain that it w r as done be- 
fore 1811 ; but, correctly interpreted, this observation had 
been almost the great discovery. To conclude our review 
of the claims of Walker, there can be no doubt of the fact 
that he was the first to distinctly assign motion and sensa- 
tion to the different roots of the spinal nerves, though he 
incorrectly ascribed motor properties to the posterior roots 
and sensory properties to the anterior, and brought forward 
not one iota of proof in support of his theories. 

The claims of Mayo to the discovery of the distinct 
properties of the roots of the spinal nerves are very indefi- 
nite. He simply states, long after the publication of the 
experiments of Magendie, that the "remarkable analogy 
which exists between the fifth nerve and the spinal nerves 

1 WALKER, The Nervous System, anatomical and physiological : in which the 
functions of the various parts of the brain are for the first time assigned, and to 
which is prefixed some account of the author's earliest discoveries, of which the 
more recent doctrine of Bell, Magendie, etc., is shown to be at once a plagiarism, an 
inversion, and a blunder, associated with useless experiments, which they have nei- 
ther understood nor explained, London, 1844, p. 50, et seg. 

* WALKER, op. cit., p. 18. 



MOTOR AND SENSORY NERVES. 69 

ied me to suppose that the two roots of the spinal nerves 
had the same discrepancy of function with the two roots of 
the fifth ; and that the ganglionic portion might belong to 
sensation, the smaller anterior portion to volition." 1 

As we shall see farther on, all discussion relative to pri- 
ority in the discovery of the true functions of the roots of the 
nerves is confined to the claims of Bell and of Magendie. The 
experiments of Miiller 3 and others were made after 1822, the 
date of the first publication of the experiments of Magendie. 

In nearly every. treatise on physiology published since 
1822, and in almost all works on the nervous system subse- 
quent to that date, the great discovery of the distinct seat 
of motion and sensation in the spinal nerves is a scribed to 
Sir Charles Bell. The name of Magendie is seldom men- 
tioned in this connection, even in France ; and his discov- 
eries are supposed to relate chiefly to the seat of sensation 
and motion in the different columns of the spinal cord. 

It is unnecessary to enlarge upon the importance of the 
discovery that the anterior roots of the spinal nerves are 
motor, and the posterior, sensory, and that the union of these 
two roots in the mixed nerves gives them their double 
properties, for we can hardly imagine a physiology of the 
cerebro-spinal nervous system without this fact as the starting- 
point ; and we have entered, rather more elaborately than 
usual, into an historical review of this discovery, from the 
fact that nearly all writers have ascribed it to Sir Charles 
Bell, and have ignored the claims of Magendie, the real dis- 
coverer. In an article published in English, in October, 
1868, 3 and in French, during the same year, 4 we have given 

1 MAYO, Outlines of Human Physiology, London, 1827, p. 240. 

2 MULLER, Physiologic du systeme nerveux, Paris, 1840, tome i., p. 85, et seq. ; 
and, Manuel de physiologic, Paris, 1851, tome i., p. 598, et seq. The experiments 
of M tiller were first published in 1831. 

3 FLINT, JR., Historical Considerations concerning the Properties of the Roots 
of the Spinal Serves. Quarterly Journal of Psychological Medicine, New York, 
1868, vol. ii., p. 625, et seq. 

4 Journal de ranatomie, Paris, 1868, tome v. r p. 520, et seq., and p. 575, et seq. 



70 NEKVOUS SYSTEM. 

an elaborate review of the whole subject, being prompted to 
do so by the perusal of what purported to be an exact reprint 
of the original pamphlet by Charles Bell. 1 This pamphlet 
was printed for private circulation in 1811, and was never 
published. It has been entirely inaccessible, and its con- 
tents were only to be divined by references and quotations 
in the subsequent writings of Sir Charles Bell and of his 
brother-in-law, Mr. Shaw. 

Physiological literature does not present another instance 
of the merit of a great discovery resting upon references to 
an unpublished pamphlet, which no student could possibly 
consult in the original, none of these references, upon close 
analysis, proving to be entirely distinct and satisfactory. It 
is not to be wondered at, therefore, that in our study of the 
origin of one of the greatest discoveries of all ages, a reprint 
of the original memoir should be examined with the most 
critical care. That this reprint was correct, seemed probable 
from a comparison of its text with the quotations from 
the original to be found in the writings of Sir Charles Bell 
and Mr. Shaw, and from the testimony of reviewers who 
claimed to have compared it with the original. 8 "Within a 
short time, however, an authorized reprint in full, from a 
manuscript in the hands of the widow of the author, has ap- 
peared in the Journal of Anatomy? This reprint corre- 
sponds exactly with the text in the "Documents and Dates" 

"When the only reprint of the celebrated pamphlet of Sir 
Charles Bell was itself excessively rare, as is the case with 
the "Documents and Dates" we thought it desirable to 
make long quotations to show the ideas entertained by 

1 Documents and Dates of Modern Discoveries in the Nervous System, London, 
Jolm Churchill, 1839, p. 37, et seq. 

2 The London Medical and Physical Journal, 1829, vol. Ixii., p. 525, and voL 
Ixiii., p. 40. The British and Foreign Medico- Chirurgical Review, London, 1840, 
vol. ix., p. 98. 

3 Reprint of the "Idea of a new Anatomy of the Brain ; submitted for the 
Observations of his Friends,' 1 ' 1 by CHARLES BELL, F. R. S. E. Journal of Anatomy 
and Physiology, Cambridge and London, 1869, vol. in., p. 147, et seq. 



MOTOR AXD SENIORY NERVES. 71 

Bell regarding the properties of the two roots of the spinal 
nerves ; but now that an authorized reprint can be so readily 
consulted, it is only necessary to refer to this to show that 
Bell did not at that time regard the anterior roots as motor 
and the posterior roots as sensory, but that he thought that 
the anterior roots were for both motion and sensation and 
the posterior roots presided over "the secret operations of 
the bodily frame, or the connections which unite the parts 
of the body into a system." l 

All the credit which we have to give to Sir Charles Bell 
for advances in the anatomy and physiology of the spinal 
nerves must cease with the review of the pamphlet of 1811. 
In a memoir on the nerves of the head, read before the 
Royal Society, July 12, 1821, more than a year before the 
publication of the experiments of Magendie, there is no men- 
tion of distinct motor and sensitive roots of the spinal nerves, 
nor of distinct properties in different portions of the spinal 
cord. This paper was republished by Bell, after the pub- 
lication of Magendie' s observations, in a work on the nervous 
system ; and it is this republication which is most accessible 
and most frequently referred to by physiological writers. 
The republication avowedly contains " some additional ex- 
planations ; " but a careful comparison of it with the original 
shows that every portion of it that was susceptible of such 
verbal alteration had been modified to make it correspond 
with the discovery by Magendie. But, at the same time, the 
impression received by the reader is, that it is essentially the 
same as the memoir published in 1821. 3 'In the controver- 
sial condition of the question at the time of this republication, 
the alterations and " additional explanations " ought certainly 

1 In a paper read before the Medico-Chirurgical Society, in April, 1822, Mr. 
J. Shaw gives the date of the first paper by Charles Bell, as 1809. This error is 
quoted into many reviews and other publications, but it has been corrected by 
Bell himself, and by Mr. A. Shaw. (ALEXANDER SHAW, Narrative of the Discov- 
eries of Sir Charles Sell in the Nervous System, London, 1830, p. 14.) 

8 CHARLES BELL, The Nervous System of the Human Body, London, 1844, p, 
33 et seq. 



72 NERVOUS SYSTEM. 

to have been distinctly indicated in the text ; but in a reprint 
of the paper of 1821, in 1830, there is no indication to the 
reader that any change had been made from the original, 
though every expression bearing upon the question is made 
to correspond with the information derived from the discov- 
eries of Magendie. 1 This is a subject which we have no 
desire to pursue farther than is necessary to vindicate the 

1 CHARLES BELL, The Nervous System of the Human Body, embracing the 
Papers delivered to the Royal Society on the Subject of the Nerves, London, 1830, 
p. 55, et seq. 

In the appendix to the work on the Nervous System, published in 1844, 
the claim to the discovery of the distinct functions of the anterior and posterior 
roots of the spinal nerves is distinctly made by Sir Charles Bell, who refers to 
the experiments detailed in the pamphlet of 1811. It will be seen by the fol- 
lowing extract, as compared with the extracts which we have made from the 
pamphlet, that the statements by Sir Charles Bell as to what wa's contained in 
this pamphlet are incorrect and calculated to convey an erroneous idea with 
regard to the nature of the observations, printed in 1811, but inaccessible, and 
of the deductions made at that time. 

" Long before this (1811) I wrote a little book, put it into the hands of my 
friends, and had it printed and distributed ; it contained (excuse me in saying it) 
this great principle that a nerve, whatever its nature may be, cannot perform 
two functions at once pit cannot convey sensation inward to the sensorium at 
the same moment that it carries outward a mandate of the will to the muscles, 
whether it be through the means of a fluid, or an ether, or a vibration, or what 
you will, that it performs its function. Two vibrations cannot run counter 
through the same fibre, and at the same instant ; two undulations cannot go in 
different directions through the same tube at the same moment ; and therefore I 
conceived that the nerves must be different in their kind. This led me to ex- 
periment upon the nerves of the spine ; for I said : ' Where shall I 1 be able to find 
a nerve with the roots separated? Where shall I be able to distinguish the 
properties of a compound nerve ? By experimenting upon the separate roots 
of the spinal nerves. ' So, then, taking a fine instrument, the point of a needle, 
and drawing it first along one set of roots, and then along the other, I found 
that, as I touched one set the anterior roots it was like touching the key of 
a piano-forte, all the cords, as it were the muscles were in vibration ; and 
when I touched the other there was pain and struggling. That would not do ; 
the animal being alive to sensation, there was confusion here ; and therefore I 
struck the animal on the head, and then I made my experiments clearly ; by 
which it was shewn, that the roots of these nerves were of different qualities, 
one obviously bestowing motion ; and, by inference, the other bestowing scnsi- 
bility" (The Nervous System, etc., London, 1844, p. 285). 



MOTOR AND SENSORY NERVES. T3 

scientific record of the last-named physiologist ; and if the 
good taste of these allusions be called in question, we have 
only to ask that the review in the Psychological Journal or 
in the Joui*nal de Panatomie be consulted, and that the 
comparisons there made be verified. The same criticisms of 
the alterations in the republished memoirs of Sir Charles 
Bell have been made by Yulpian. 1 Among English writers, 
the relative claims of Bell and Magendie have been correctly 
reviewed by a writer in the London Medical and Physical 
Journal, in 1829, a and by Elliotson, in 1840. 8 Bernard, who 
formerly ascribed the discovery to Bell, has lately recognized 
fully the claims of Magendie. 4 

The first publications of Magendie concerning the anat- 
omy and the functions of different portions of the nervous 
system appeared in the Journal de physiologie, in 1821. In 
the first volume of this journal, is a notice of the researches 
of Charles Bell on the nerves of the face, with an account 
of the observations of Mr. Shaw on the same subject.* Ma- 
gendie here states that he repeated the experiments of Bell 
with MM. Shaw and Dupuy at Alfort. 6 He had not at that 
time received the memoir of Bell ; but in a succeeding num- 

1 VULPIAN, Lemons sur la physiologic ginirale et comparee du systeme nerveux, 
Paris, 1866, pp. 109 and 127. 

8 The London Medical and Physical Journal, 1829, voL IxiL, p. 532. 

3 ELLIOTSON, Human Physiology, London, 1840, p. 465. 

4 BERNARD, Lemons sur la physiologic et la pathologic du systeme nerveux, 
Paris, 1858, tome i., p. 20, et seq. Even Bernard, a pupil, and for a long time 
the preparateur for Magendie, at one time seemed to regard Sir Charles Bell as 
the discoverer of the functions of the roots of the spinal nerves (ibid., p. 25 ; and, 
Lemons sur les effete des substances toxigues et medicamenteuses, Paris, 1857, p. 
20) ; in a late work, however, in which this whole subject is reviewed, the claims 
of Magendie to the discovery are fully recognized (BERNARD, Rapport sur le pro- 
gres ct la marche de la physiologic generale en France, Paris, 1867, pp. 12 and 
154). Bernard states that he was unable to obtain the original memoir of Bell, 
printed in 1811, but finally procured an exact copy, which is probably the reprint 
of 1839. (Ibid., p. 155.) 

6 CHARLES BELL, Recherches anatomiques et physiologiques sur le system* 
nerveux. Journal de pkysiologie, Paris, 1821, tome i., p. 384, et seq. 
6 Loc. tit., p. 387. 



74: NERVOUS SYSTEM. 

ber of the journal, lie gives a full analysis of it. 1 In this 
number, also, he speaks of having repeated the experiments. 
In the same journal, follows a translation of the experiments 
of Mr. Shaw. 2 In none of these publications is there any 
allusion to the properties of the anterior and posterior roots 
of the spinal nerves, nor is there any evidence that either 
Bell, Shaw, or Magendie knew any thing about the distinct 
seat of motion and sensation in the spinal cord and the spi- 
nal nerves. 3 

In August, 1822, Magendie published his first experi- 
ments on the functions of the roots of the nerves. 4 Unlike 
any of the observations made by Charles Bell on the spi- 
nal nerves, these were made upon living animals. The spi- 
nal canal was opened, and the cord, with the roots of the 
nerves, exposed. The posterior roots of the lumbar and sacral 
nerves were then divided upon one side and the wound united 
with sutures. The result of this observation was as follows : 

" I thought at first that the limb corresponding to the 
divided nerves was entirely paralyzed ; it was insensible to 
pricking and to the most severe pinching, it also appeared 
to me to be motionless ; but soon, to my great surprise, I 
saw it move in a very marked manner, although the sensi- 
bility was still entirely extinct. A second, a third experi- 
ment, gave me exactly the same result ; I commenced to 
regard it as probable that the posterior roots of the spinal 
nerves might have functions different from the anterior roots, 
and that they were more particularly devoted to sensibility." 6 

1 BELL, Suite de recherches anatomiques et pliysiologiques sur le systeme nervewx. 
Journal de physiologic, Paris, 1822, tome ii., p. 66, et seq. 

2 SHAW, Experiences sur le systeme nerveux. Extrait et traduit de V Anglais 
par M. Cairns. Journal de physiologic, Paris, 1822, tome ii., p. 77, et seq. 

3 In the same volume of the journal (p. 363), Magendie gives an account of 
Bell's observations on the respiratory nerves of the chest, which were presented 
to the Royal Society, May 2, 1822. 

4 MAGENDIE, Experiences sur le* fonctions des racines des nerfs rachidiens. 
Journal de physiologic, Paris, 1822, tome ii., p. 276, et seq. 

5 Ibid., p. 277. 



MOTOR AND SENSORY NERVES. 75 

The experiments in which the anterior roots were di- 
vided were no less striking : 

"As in the preceding experiments, I only made the 
division upon one side, in order to have a term of compari- 
son. One can conceive with what curiosity I followed the 
effects of this division ; they were not at all doubtful, the 
limb was completely motionless and flaccid, while it pre- 
served a marked sensibility. Finally, that nothing should 
be neglected, I divided at the same time the anterior and 
the posterior roots ; then followed absolute loss of sensation 
and of motion." 1 

Prom these experiments Magendie drew the following 
conclusions : 

" I am following out my researches, and will give a more 
detailed account of them in the following number ; it is suf- 
ficient for me to be able to announce at present as positive, 
that the anterior and the posterior roots of the nerves which 
arise from the spinal cord have different functions, that the 
posterior seem more particularly devoted to sensibility, 
while the anterior seem more especially connected with 
motion." 2 

In the second note, published in the same volume of the 
Joui-nal de physiologie^ Magendie exposed and irritated the 
two roots of the nerves, with the following results : 

" I commenced by examining in this regard the poste- 
rior roots, or the nerves of sensation. The following is the 
result which I observed : on pinching, pulling, or pricking 
these roots, the animal manifested pain ; but this was not to 
be compared as regards intensity with that which was 'de- 
veloped if the spinal cord were touched, even lightly, at 
the point of origin of the roots. Nearly every time that 
the posterior roots were thus stimulated, contractions were 
produced in the muscles to which the nerves were distrib- 
uted ; these contractions, however, are not well marked, 
and are infinitely more feeble than when the cord itself is 

1 Ibid., p. 278. ' Ibid., p. 279. 



76 



NERVOUS SYSTEM. 



touched. "When, at the same time, a bundle of the poste- 
rior root is cut, there is produced a movement in totality in 
the limb to which the bundle is distributed. 

" I repeated the same experiments on the anterior roots, 
and I obtained analogous results, but in an opposite sense ; 
for the contractions excited by the contusion, the pricking, 
etc., are very forcible, and even convulsive, while the signs 
of sensibility are hardly visible. These facts are, then, con- 
firmatory of those which I have announced ; only they seem 
to establish that sensation is not exclusively in the posterior 
roots, any more than motion in the anterior roots. Never- 
theless, a difficulty may arise. When, in the preceding ex- 
periments, the roots had been cut, they were attached to the 
spinal cord. Might not the disturbance communicated to 
the cord be the real cause either of the contractions or of 
the pain which the animals experienced ? To remove this 
doubt, I repeated the experiments after having separated 
the roots from the cord ; and I must say that, except in two 
animals, in which I saw contractions when I pinched or 
pulled the anterior and posterior roots, in all the other in- 
stances I did not observe any sensible effect of irritation 
of the anterior or posterior roots thus separated from the 
cord." 1 

Magendie then goes on to say that, when he published 
the note in the preceding number of the journal, he sup- 
posed that he was the first who had thought of cutting the 
roots of the spinal nerves ; but he was soon undeceived by 
a letter from Mr. Shaw, who stated that Bell had divided the 
roots thirteen years before. Magendie afterward received 
from Mr. Shaw a copy of Bell's essay (" Idea of a New Anat- 
omy of the Brain "), and, as will be seen by the following 
extract, gave Bell full credit for all his observations : 

" It is seen by this quotation from a work which I could 
not be acquainted with, inasmuch as it had not been pub- 
lished, that Mr. Bell, led by his ingenious ideas concerning 

1 Ibid., p. 368. 



MOTOR AND SENSORY NERVES. 77 

the nervous system, was very near discovering the functions 
of the spinal roots; still the fact that the anterior are de- 
voted to movement, while the posterior belong more par- 
ticularly to sensation, seems to have escaped him ; it is, 
then, to having established this fact in a positive manner 
that I must limit my pretensions." 

Such are the experiments by which the properties of the 
roots of the spinal nerves were discovered. From that time, 
the fact took its place in science, that the posterior roots are 
for sensation and the anterior for motion. Some discussion 
has arisen as to whether the anterior roots do not possess a 
certain amount of sensibility, called recurrent sensibility, 
and this question has engaged the attention of physiologists 
within, a few years ; but the distinct functions of the two 
roots have never been doubted. We have already seen what 
use Bell made of these facts in late editions of his work on 
the nervous system. Before the days of anaesthetics, expos- 
ing the roots of the nerves in the dog was very laborious, 
and painful to the animal, and the disturbances produced by 
so serious an operation interfered somewhat with the effects 
of irritation of the different roots. But now that the canal 
may be opened without pain to the animal, the experiments 
are much more satisfactory and have often been repeated by 
physiologists. We have frequently, indeed, demonstrated 
the properties of the roots of the nerves in public teaching. 2 

Although, as we have seen, almost all physiological 
writers, even in France, regarded Bell as the real discoverer, 
Magendie continued to claim that he first positively ascer- 
tained the seat of motion and sensation in the spinal nerves. 

1 Ibid., p. 371. 

9 FLINT, JR., Experiment* on the Recurrent Sensibility of the Anterior Hoots 
of the Spinal Nerves. Xew Orleans Medical Times, 1861, p. 21, et seq. 

At the time that this paper was written, we had not had an opportunity of 
consulting the original memoir of Sir Charles Bell, and, with others, regarded 
him as the discoverer of the functions of the roots of the nerves. We have 
also had occasion to modify the views therein expressed concerning the recur- 
rent sensibility of the anterior roots. 



78 NERVOUS SYSTEM. 

In 1823, after reiterating his statements with regard to the 
nerves, he extended his researches to the cord itself, and de- 
monstrated that the anterior columns were motor and the 
posterior columns sensitive. 1 In all his subsequent publica- 
tions the same statements are made." 

Shaw, in his " Narrative," states that, in 1822, Magendie 
" admitted that the experiments on the roots of the spinal 
nerves, which he had claimed as original, had been performed 
many years before by Sir Charles Bell." 3 This is not cor- 
rect ; and we have already quoted in full the passage in which 
Magendie gives Bell full credit for what he had done, but 
expressly states that the fact, that the anterior roots preside 
over movement, and the posterior, over sensation, seems to 
have escaped him. Shaw also quotes Desmoulins and Ma- 
gendie as admitting " that there is no absolute distinction 
between the functions possessed by the two roots ; " 4 but, in 
doing this, he translates the expression into English incor- 
rectly. In the passage referred to, it is stated that " L'isole- 
ment des deux proprietes dans chacun des deux ordres de ra- 
cines, n'est done pas absolu," which simply means that the 
motor roots are not absolutely without sensibility, and the 
sensory roots are not absolutely devoid of motor properties. 

The experiments of Magendie, made in 1822, must stand 
without further question as the first to demonstrate the true 
properties of the two roots of the spinal nerves ; and, before 
the publication of these experiments, no physiologist had a 
correct idea, theoretical or experimental, of the seat of motion 
and sensation in these nerves. 

1 MAGENDIE, Note sur le siege du mouvement et du sentiment dans le moelle 
epinere. Journal de physiologic, Paris, 1823, tome iii., p. 153, et seq. 

2 DESMOULINS ET MAGENDIE, Anatomie des systemes nerveux des animaux d ver- 
tebres, Paris, 1825, tome il, p. 777. 

MAGENDIE, Precis elementaire de physiologic, deuxieme edition, Paris, 1825, 
tome i., pp. 167, 216; et, quatrieme edition, 1836, tome i., pp. 200, 266. 

8 ALEXANDER SHAW, Narrative of the Discoveries of Sir Charles Bell in ihA 
Nervous System, London, 1839, p. 156. 

4 Loc. cit., p. 168. 



PROPERTIES OF THE POSTERIOR ROOTS. 79 

Properties of the Posterior Roots of the Spinal Nerves. 
It is unnecessary to follow out, from the date of the first 
experiments by Magendie to the present day, the observa- 
tions that have been made from time to time upon the prop- 
erties of the roots of the spinal nerves. For many years, the 
difficulties in operating upon animals high in the scale ren- 
dered confirmatory experiments somewhat unsatisfactory. 
The great German physiologist, J. Miiller, showed, in experi- 
ments made upon frogs, in 1831, 1 that irritation of the pos- 
terior roots produced no convulsive movements ; but he de- 
spaired of operating satisfactorily upon warm-blooded animals. 
Magendie, in his later experiments, 2 and Longet, in experi- 
ments performed on dogs, published in 18ttl, s showed verv 
satisfactorily that the posterior roots were exclusively sen- 
sory, and this fact has been abundantly confirmed by more 
recent observations upon the higher classes of animals. ITe 
have ourselves frequently exposed and irritated the roots of 
the nerves in dogs in public demonstrations, in experiments 
upon the recurrent sensibility of the anterior roots, 4 and in 
another series of observations upon the properties of the 
spinal cord, which will be referred to hereafter. 

The remarkable anatomical peculiarity of the posterior 
roots, which they have in common with all of the exclusively 
sensitive nerves, is the presence of a ganglion. While we 
have no distinct idea of the function of these ganglia in con- 
nection with the transmission of impressions from the pe- 
riphery to the centres, it has been shown to have a remark- 

1 MULLER, Nouvelles experiences sur Teffet que produit rirritation mechaniqut 
et galvanique sur les ratines des nerfs spinaux. Annales des sciences natureUes, 
Paris, 1831, tome xxiii., p. 100, et seq. 

2 MAGEXDIE, Lecons sur les fonctions et les maladies du systeme nerveux, Paris, 
1841, tome ii., p. 52, et seq., quatrieme lecon, 3 mai, 1839. 

3 LOXGET, Recherches pathologiques et experimentales sur les prcprittes et let 
fonctions des faisceauz de la moelle epinere et des racines des nerfs rachidiens. 

Archives generales de medecine, Paris, 1841, tome Ivi., p. 168, et seq. 

4 FLINT, JR., Experiments on the Recurrent Sensibility of the Anterior Roots of 
the Spinal Nerves. New Orleans Medical Times, 1861, p. 21, et sen. 

106 



80 NERVOUS SYSTEM. 

able influence upon the nutrition of the nerves after their 
division. Operating upon the second cervical nerves, in 
which the ganglia can be reached without exposing the spi- 
nal cord, Waller has demonstrated the following interesting 
facts : * 

When the roots are divided between the ganglion and the 
cord, the central end of the anterior root, attached to the 
cord, preserves its normal structure, while the peripheral end 
in a few days becomes degenerated, the tubes filled with 
granular matter, etc., and, in short, undergoes those changes 
observed in all nerves separated from their centres. On the 
other hand, in the posterior roots, the end attached to the 
cord undergoes degeneration, and the peripheral end, the 
one to which the ganglion is attached, preserves its normal 
histological characters. From these experiments, which have 
been confirmed and somewhat extended by Bernard, 9 it is 
concluded that the ganglia of the posterior roots have an in- 
fluence over the nutrition of the sensitive nerves, in the same 
way as the centres influence the nutrition of the motor 
nerves which emanate from them. These points are- inter- 
esting, as showing the existence of centres attached to the 
sensory system of nerves, which have, as far as we know, 
a purely trophic influence over tho nerves, while the active 
centres to which the motor nerves are attached regulate, to 
a certain extent, the nutrition of the nerves, and also are 
capable of generating nerve-force. We do not know that the 
ganglia of the roots of sensitive nerves have any function 
except as trophic centres. 

Properties of the Anterior Roots of the Spinal Nerves. 
The same experiments that demonstrated that the posterior 
roots of the spinal nerves are sensitive showed that the ante- 
rior roots are motor. If the two roots be exposed in an 

1 WALLER, Comptes rendus, Paris, 1857, tome xliv., p. 168. 

2 BERNARD, Lemons sur la physiologic et la pathologic du systeme nerveux, 
faris, 1858, tome i., p. 235, et seg. 



RECURRENT SENSIBILITY. 81 

animal just killed, no convulsive movements are produced 
by stimulating the posterior roots ; but if the anterior roots 
be irritated, movements of the most violent character occur, 
confined to those muscles to which the filaments of the roots 
are distributed. There has never been any doubt upon this 
point since the experiments of Hagendie ; and it is now uni- 
versally admitted by physiologists, that the motor properties 
of the mixed nerves are derived exclusively from their ante- 
rior roots of origin from the spinal cord. The question has 
arisen, however, whether the anterior roots be not also en- 
dowed with sensibility, notably less in degree than the poste- 
rior roots, but still marked and invariable. The sensibility 
observed in the anterior roots is abolished by section of the 
posterior roots ; and this property, which is thought to be 
derived from the posterior roots, has been called recurrent 
sensibility. 

Recurrent Sensibility. We have seen, in reviewing the 
history of the discovery of the distinct function of the roots 
of the spinal nerves, that even in the earliest experiments by 
Magendie, it appeared that the anterior roots possessed sen- 
sibility in a certain degree, though it was insignificant as com- 
pared with the sensibility of the posterior roots. In his later 
experiments, Magendie formularized these facts, and an- 
nounced that the anterior roots were sensitive as well as 
motor, but less sensitive than the posterior roots, and that 
this sensibility was abolished when the posterior roots were 
divided. 1 Later still, he failed to demonstrate this sensibility 
of the anterior roots ; but it was finally shown that this oc- 
curred in animals exhausted from pain and loss of blood, and 
that the anterior roots were really sensitive under normal 
conditions. 3 Longet claims to have discovered, in 1839, what 

1 MAGENDIE, Lemons sur les fonctions et les maladies du sysleme nerveux, Paris, 
1841, tome ii., pp. 63, 78, quatrieme legon, 3 mai, 1839, cincjuieme lepon, 8 mai, 
1839.. 

2 MAGEXDIE, Note sur la sensibilite recurrente ; Extrait des comptes 
Paris, juin, 1847, tome xxiv., p. 3. 



82 NERVOUS SYSTEM. 

is now known as the recurrent sensibility of the anterior 
roots, and to have communicated his views to Magendie ; ' 
but the publications on the subject and the testimony of 
Bernard, 2 who witnessed all the experiments in the labora- 
tory of the College of France, as well as the observations of 
Magendie, in 1822, leave no doubt that he was the first to 
note the sensibility of these roots. 

The experimental facts with regard to the recurrent sen- 
sibility are very simple. If the two roots of a spinal nerve 
be exposed, and if the animal be allowed to recover, by a 
few hours' repose, from the shock of the operation, irrita- 
tion of the posterior root will produce pain and the general 
movements incident to it, but no localized contractions of 
muscles; and irritation of the anterior root will produce 
contraction of certain muscles and a certain amount of pain, 
always less, however, than the pain resulting from stimula- 
tion of the posterior roots. If the anterior root be divided, 
the end attached to the cord will be found completely insen- 
sible, but the peripheral end will manifest the same sensibili- 
ty as the undivided root ; showing that the sensory proper- 
ties of the anterior roots are not derived from the cord. If 
the posterior root be divided, the sensibility of the anterior 
root is instantly abolished ; showing that the sensibility of 
the anterior root is recurrent, being derived from the poste- 
rior root through the periphery. With regard to these facts 
there can be no doubt, and we ourselves verified them in a 
series of experiments published in 1861. 3 Experiments have 
simply demonstrated the fact that the recurrent sensibility 
comes through the periphery, without actually showing any 
recurrent fibres ; and division of a mixed nerve after the 
nnion of the two roots deprives the anterior root of its scn- 

1 LONGET, Traite de physiologic, Paris, 1869, tome Hi., p. 115. 

2 BERNARD, Lemons sur la physiologic et la pathologic du syst&me nerveux, Paris, 
1858, tome i., p. 35. 

3 FLINT, JR., Experiments on the Recurrent Sensibility of the Anterior Roots of 
ffte Spinal Nerves. New Orleans Medical Times, 1861, p. 21, et seq. 



RECURRENT SENSIBILITY. 83 

sibility, showing that the recurrent fibres, if they exist, must 
turn back near the periphery. 1 

The question now arises with regard to the exact mech- 
anism of recurrent sensibility. The explanation offered by 
Magendie and Bernard is, that there are actually fibres re- 
turning from the posterior to the anterior roots ; that these 
fibres are, of course, sensitive, and that irritation of the an- 
terior roots is propagated toward the periphery, and returns 
to the centres through the posterior roots. This explanation 
satisfies all of the experimental conditions, and is further 
sustained by the microscopical examinations of Schiff, and 
of Philipeaux and Yulpian. It will be remembered that the 
ganglia of the posterior nerves, after division of these roots, 
have the remarkable power of preserving the anatomical 
integrity of the fibres to which they are attached. Now, 
it has been shown by Schiff that, after division of the pos- 
terior roots beyond the ganglia, the anterior roots contain 
altered fibres, which he believes come from the posterior 
roots, and give to these roots their sensibility. Philipeaux 
and Yulpian, in experiments on the regeneration of nerves, 
showed that the peripheral ends of the sublingual and facial 
nerves remained sensitive after division, and that after ten 
or fifteen days, in the midst of a great mass of degenerated 
fibres, were a few that possessed their normal characters. 3 
The bearing of these facts will be better understood by re- 
ferring back to the experiments of Waller on the influence 
of the ganglia over the nutrition of sensitive nerves. 3 

Dr. Brown-Sequard offers a different explanation of the 
pain developed upon irritation of the anterior roots. He 
believes this to be due entirely to cramp or convulsive con- 
traction of the muscles. 4 This may be accepted, perhaps, as 

1 BERNARD, Systeme nerveux, Paris, 1858, tome i., p. 28. 

8 VULPIAX, Lemons sur la physiologic generate ef. comparee du systeme ncrveux, 
Paris, 1866, p. 150. ' See page 80. 

4 BROWN-SKQUARD, Course of Lectures on the Physiology and Pathology of the 
Central Nervous System, Philadelphia, 1860, p. 8. 



84 NERVOUS SYSTEM. 

a partial explanation ; for there can be no doubt of the fact 
that violent muscular action, produced independently of vo- 
lition, is more or less painful ; but it does not explain the 
great sensibility sometimes observed when the muscular 
contraction is comparatively feeble. There can be hardly 
any doubt that the explanation offered by Magendie, and 
sustained by the ingenious histoiogical observations cited 
above, is in the main correct. 

Mode of Action of the Motor Nerves. Having estab- 
lished the anatomical distinction between the motor and 
sensory nerves, it becomes necessary to study the differences 
in the mode of action of these two kinds of nervous con- 
ductors. In the first place, it is evident, taking the nerves 
and their roots as we find them in, the organism in a normal 
condition, that certain fibres act from the centres to the pe- 
riphery, conducting motor stimulus, while others act from 
the periphery to the centres, conducting sensory impres- 
sions; but within a few years, certain experiments have 
raised the question, whether sensory fibres may not be made 
to conduct the motor stimulus, and vice versa. The experi- 
ments to which we allude have already been referred to in 
connection with the regeneration of nerves ; 1 and they show 
that when a sensory and a motor branch, situated near 
enough together, be divided, and the peripheral extremity 
of one be connected with the central extremity of the other, 
after a time union will take place, and the motor filaments 
will conduct sensory impressions, and the sensory filaments 
will conduct the motor stimulus. This is a most curious 
and interesting experimental fact ; but it is no argument 
against the distinct seat of motion and sensation in the ner- 
vous system. 

As regards the motor nerves, the force, whatever it may 
be, generated in the centres, is conducted from the centres 
to the peripheral distribution of the nerves in the muscles, 

1 See page 62. 



MODE OF ACTION OF THE MOTOR NERVES. 85 

and is here manifested by contraction. Their mode of ac- 
tion, therefore, is centrifugal. "When these motor filaments 
are divided, the connection between the parts animated by 
them and the centre is interrupted, and motion in these 
parts, in obedience to the natural stimulus, becomes impossi- 
ble. But, while we cannot induce generation of nerve-force 
in the centres by the direct application of any agent to 
them, this force may be imitated by stimulation applied to 
the nerve itself. A nerve that will respond to direct stimu- 
lation is said to be excitable ; but this property does not ex- 
tend throughout the entire conducting motor system. For 
example, we shall see when we come to study the properties 
of the encephalon, that certain fasciculi capable of conduct- 
ing the motor stimulus from the centres to the muscles are 
not affected by direct stimulation, and seem to be inexcit- 
ablc. 

If a motor nerve be divided, galvanic, mechanical, or 
other stimulation applied to the extremity connected with 
the centres produces no effect ; but the same stimulation 
applied to the extremity connected with the muscles is fol- 
lowed by contraction. The phenomena indicating that a 
nerve retains its physiological properties are always mani- 
fested at its peripheral distribution, and do not essentially 
vary when the nerve is stimulated at different points in its 
course. For example, stimulation of the anterior roots near 
the cord produces contraction in those muscles to which 
the fibres of these roots are distributed ; but the same effect 
follows stimulation of the nerve going to these muscles in 
any part of its course. 

As far as their physiological action is concerned, the dif- 
ferent nerve-fibres are entirely independent, and the rela- 
tions which they bear to each other in the nervous fasciculi 
and in the so-called anastomoses of nerves involve simple 
contiguity. If we compare the nerve-force to galvanism, 
each individual fibre seems completely insulated ; and a stim- 
ulus conducted by it to muscles never extends to the adjacent 



00 NERVOUS SYSTEM. 

fibres. That it is the axis-cylinder which conducts and the 
medullary tube which insulates, it is impossible to say with 
positiveness ; but, as we have already seen, it is move than 
probable that the central band is the only conducting ele- 
ment. , 

We have incidentally noted the fact that direct stimula- 
tion applied to the centres, even when the connection between 
these and the muscles is perfect, is incapable of inducing the 
generation of nerve-force ; but the generation of a motor 
stimulus may be induced by an impression made upon sen- 
sitive nerves and conveyed by them to the centres. If, for 
example, we isolate a certain portion of the central nervous 
system, as the spinal cord, and leave its connections with 
the motor and sensitive nerves intact, these phenomena may 
be readily observed : An impression made upon the -sensi- 
tive nerves will be conveyed to the gray matter of the cord 
and will induce the generation of a motor stimulus by the 
cells of this part, which will be conducted to the muscles 
and give rise to contraction. As the stimulus, in such ob- 
servations, seems to be reflected from the cord through the 
motor nerves to the muscles, this action has been called 
reflex. These phenomena constitute an important division 
in the physiology of the nervous system, and will be fully 
considered by themselves. 

Associated Movements. It is well known that the action 
of certain muscles is with difficulty isolated by an effort of 
the will. This applies to sets of muscles on one side of the 
body and to corresponding muscles upon the two sides. 
For example, it is almost impossible, without great practice, 
to move some of the fingers, restraining the movements of 
the others ; and the action of certain sets of muscles of the 
extremities is always simultaneous. The toes, which are but 
little used as the foot is confined in the ordinary dress, are 
capable of very little independent action. It is difficult to 
move o?ie eye without the other, or to make rapid rotary 



ASSOCIATED MOVEMENTS. 8T 

movements of one hand, while an entirely different order of 
movements is executed by the other ; and instances of this 
kind might be multiplied. 

In studying these associated movements, the question 
arises as to how far they are due to the anatomical relations 
of the nerves to the centres and their connections with mus- 
cles, and how far they depend upon habit and exercise. "We 
can imagine that there are certain sets of nerve-cells, con- 
nected with each other by commissural fibres and giving ori- 
gin to motor nerves distributed to sets of muscles ; an ana- 
tomical arrangement that might render a separate action of 
these cells impossible. The anatomy of the nerve-centres 
and their connection with fibres are so difficult of investiga- 
tion, that demonstrative proof of the existence of such sys- 
tems is impracticable ; but this affords a ready explanation 
of the fact that we cannot, as a rule, by an effort of the 
will, cause a portion only of a single muscle to contract ; yet 
some of the larger muscles receive an immense number of 
motor nerve-fibres which are probably connected with gray 
matter composed of numerous anastomosing cells. 

Many of the associated movements are capable of being 
influenced to a surprising degree by education, of which no 
better example can be found than in the case of skilful per- 
formers upon certain musical instruments, such as the piano, 
harp, violin, and other stringed instruments. In the tech- 
nical study of such instruments, not only does one hand be- 
come almost independent of the other, but very complex 
associated movements may be acquired. An accomplished 
pianist or violinist executes the different scales automati- 
cally by a single effort of the will, and frequently pianists 
execute at the same time scales with both hands, the action 
being entirely opposed to the natural association of move- 
ments. Feats of sleight of hand also show how wonderfully 
the muscles may be educated, and to what an extent the 
power of association and disassociation of movements may 
be acquired by long practice. 



88 NERVOUS 81' STEM. 

Looking at the associated movements in their relations 
to the mode of action of the motor nerves, it seems prob- 
able that, as a rule, the anatomical relations of the nerves 
are such that a motor stimulus, or an effort of the will, can- 
not be conducted to a portion only of a muscle, but must act 
upon the whole muscle, and the same is true, probably, of 
certain restricted sets of muscles ; but the association of 
movements of corresponding muscles upon the two sides 
of the body, with the exception, perhaps, of the muscles of 
the eyes, is due mainly to habit, and may be greatly modi- 
fied by education. 

Mode of Action of the Sensory Nerves. The sensory 
nerve-fibres, like the fibres of the motor system, are en- 
tirely independent of each other in their action; and in 
the so-called anastomoses that take place between sensory 
nerves, the fibres assume no new relations, except as regards 
contiguity. 

As motor fibres convey to their peripheral distribution 
the stimulus engendered by an irritation applied in any por- 
tion of their course, so an impression made upon a sensitive 
nerve is always referred to the periphery. A familiar 
example of this is afforded by the very common accident of , 
contusion of the ulnar nerve as it passes between the ole- 
cranon and the condyle of the humerus. This is attended 
with painful tingling of the ring and little finger and other 
parts to which the filaments of this nerve are distributed, 
without, necessarily, any pain at the point of injury. More 
striking examples are afforded in neuralgic affections depend- 
ent upon disease or pressure on the trunk of a sensitive 
nerve. In such cases, excision of the nerve is often practised, 
but no permanent relief follows unless the section be made 
between the affected portion of the nerve and the nerve- 
centres ; and the pain produced by the disease is always re- 
ferred to the termination of the nerve, even after it has been 
divided between the seat of the disease and the periphery, 



MODE OF ACTION OF THE SENSORY NERVES. 89 

leaving the parts supplied by the nerve insensible to direct 
irritation. In cases of disease it is not unusual to note great 
pain in parts of the skin that are insensible to direct impres- 
sions. 1 The explanation of this is, that the nerves are par- 
alyzed near their terminal distribution, so that an impres- 
sion made upon the skin cannot be conveyed to the senso- 
riuin ; but that the trunks of the nerves still retain their 
conducting power and are the seat of diseased action, produ- 
cing pain, which is referred by the patient to the periphery. 

In multiplying examples showing the mode of action of 
the sensoiy nerves, we may refer to the sensations experi- 
enced after certain plastic operations. In the very common 
operation of restoring the nose by transplanting skin from 
the forehead, after the operation has been completed, the 
skin having been entirely separated and cicatrized in its new 
relations, the patient feels that the forehead is touched when 
the finger is applied to the artificial nose. After a time, 
however, the sensorium becomes accustomed to the new 
arrangement of the parts, and this deceptive feeling disap- 
pears. 

There are certain curious nervous phenomena, that are 
not without physiological interest, presented in persons who 
have suffered amputations. It has been long observed that 
after loss of a limb the sensation of the part remains and pain 
is frequently experienced referred to the amputated member. 
Thus a patient will feel distinctly the fingers or toes after an 
arm or a leg has been removed, and irritation of the ends of 
the nerves at the stump produces sensations referred to the 
missing member. A few years since, we observed a very 
striking example of this in a soldier who had suffered ampu- 
tation of the leg. While this patient was walking about on 
crutches, before the stump had entirely healed, on getting up 
suddenly from his seat, he attempted to walk, and put the 
stump to the ground, producing considerable injury. His 
explanation was, that he felt the foot perfectly, and it was 

1 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 178. 



90 NEKVOUS SYSTEM. 

necessary for him to be constantly on his guard to prevent 
such an accident. 

A very curious fact has been observed with regard to the 
imaginary presence of limbs after amputation, which we have 
had ample opportunities of verifying. After a time the 
sense of possession of the lost limb becomes blunted, and 
may, in some cases, entirely disappear. This may take place 
a few months after the amputation, or the sensations may 
remain in their full intensity for years. Examples are 
reported by Miiller where the sense was undiminished thir- 
teen, and, in one case, twenty years after amputation. 1 In 
a certain number of cases, however, the sense of the inter- 
mediate part is lost, the feeling in the hand or foot, as the 
case may be, remaining as distinct as ever, the impression 
being that the limb is gradually becoming shorter. These 
curious facts, noted by M. Gueniot, 2 show that the sense of 
the limb becoming shorter is observed in about half of the 
cases of amputation in which cicatrization goes on regu- 
larly ; and in these cases, the patient finally experiences a 
feeling as though the hand or foot were in direct contact 
with the stump. By careful inquiries among a large num- 
ber of patients in military hospitals, we have been enabled 
to verify these observations in the most satisfactory manner. 

1 MULLER, Elements of Physiology, London, 1840, vol. i., p. 746. 

2 GUENIOT, D"une hallucination du toucher (ou heterotophie subjective des extre 
mites) particuliere a certains ampules. Journal de la physiologic, Paris, 1861, 
tome iv., p. 416, et seq. 



CHAPTEE HI. 

GENERAL PROPERTIES OF THE NERVES. 

Nervous irritability Different means employed for exciting the nerves Disap- 
pearance of the irritability of the motor and sensory nerves after exsection . 
Nerve-force Non-identity of nerve-force with electricity Rapidity of 
nervous conduction Estimation of the duration of acts involving the nerve- 
centres Action of electricity upon the nerves Contrasted action of the 
direct and the inverse current on closing and opening the circuit Voltaic 
alternations Induced muscular contraction Galvanic current from the 
exterior to the cut surface of a nerve Effects of a constant galvanic cur- 
rent upon the nervous irritability Electrotonus, anelectrotonus, and cathe- 
lectrotonus Neutral point Negative variation. 



experiments have been made, especially upon 
the cerebro-spinal nerves, with regard to their action under 
different kinds of stimulation, the probable nature of the 
nervous agent, or nerve-force, the extent and duration of 
their excitability and sensibility, etc., which have developed 
facts of more or less physiological interest and importance. 
As far as the nerves of general sensibility are concerned, the 
phenomena of conduction of impressions are essentially the 
same in all, if we except certain variations in different 
nerves as regards the degree of sensibility. The motor 
nerves all respond in the same manner to stimulation ; and 
it is upon this portion of the nervous system that the most 
important observations have been made. This being the 
case, it is evident that the cerebro-spinal nerves, in their 
behavior under the experimental conditions above enumer- 
ated, possess certain general properties, and that the functions 
of special nerves are to be studied, after a full consideration 



92 NEKVOUS SYSTEM. 

of these general properties, in connection with their anatom- 
ical distribution to the different organs in the economy. 

The points to be considered, aside from the simple divis- 
ion of the nerves into motor and sensory, are as follows : 

1. The conditions of excitability and sensibility of the 
nerves, or what is known as nervous irritability. 

2. The nature of the nervous agent, or the so-called 
nerve-force. 

3. Certain phenomena following the application of elec- 
tricity to the nerves. 

Nervous Irritability. We have already alluded in a 
general way to what is known as nervous irritability. 1 The 
term is used by physiologists to express the condition of 
nerves which enables them to respond to artificial stimula- 
tion, or to conduct the natural stimulus or external impres- 
sions. So long as a nerve retains this property it is said to 
be irritable. Of course, while in a normal condition and dur- 
ing life, irritability, as applied to nerves, simply means that 
these parts are capable of performing their peculiar functions ; 
but, after death, for a certain time the nerves will respond to 
artificial stimulation ; and it is to this property that the term 
"irritability" seems to be most applicable. At a certain 
time after death, varying in different classes of animals with 
the activity of their nutrition, the irritability of the nerves 
disappears. This occurs very soon in warm-blooded animals, 
but is later in animals lower in the scale, so that the latter 
present the most favorable conditions for experimentation. 
Most observations on nervous irritability, indeed, have been 
made upon frogs and other cold-blooded animals. Analo- 
gous facts have already been noted with regard to the mus- 
cular system, although, as we have seen, the irritability of 
the muscular tissue is entirely distinct from that of the 
nerves. 51 

Immediately or soon after death, when the irritability of 

1 See page 66. 2 See vol. iii., Movements, p. 464. 



NERVOUS IRRITABILITY. 



93 



the nerves is at its maximum, they may be excited by me- 
chanical, chemical, or galvanic stimulus, all of these agents 
producing contraction of the muscles to which the motor fila- 
ments are distributed. Mechanical irritation, simply pinch- 
ing a portion of the nerve, for example, produces a single 
muscular contraction; but if the injury to the nerve be such 
as to disorganize its fibres, that portion of the nerve will 
no longer conduct a stimulus. Among the irritants of this 
kind, we may cite the extremes of heat and cold. If an ex- 
posed nerve be cauterized, a vigorous muscular contraction 
follows. The same effect, though less marked, may be pro- 
duced by the sudden application of intense cold. Among 
chemical reagents, there are some that excite the nerves and 
others which produce no effect ; but these are not important 
from a physiological point of view. Suffice it to say that 
mechanical irritation and the action of certain chemicals are 
capable of exciting the nerves ; but that when their action 
goes so far as to disorganize the fibres, the conducting power 
of these fibres is lost. "While, however, irritation of the 
nerve above the point of injury has no effect, stimulation 
between this point and the muscles is still followed by con- 
traction. 

The most convenient method of exciting the nerves in 
physiological experiments is by means of electricity, a stimu- 
lus more closely resembling the nerve-force than any other, 
and one which may be employed without disorganizing the 
nerve-tissue, and consequently admits of extended and re- 
peated application. The action of electrfcity, however, with 
the methods of preparing the nerves and muscles for experi- 
mentation, will be fully considered under a separate head. 

The irritability of the motor system is entirely distinct 
from that of the sensory nerves, and one may be destroyed, 
leaving the other intact. This follows almost as a matter of 
course upon the fact of the anatomical distinction between 
motor and sensory nerves ; but it is interesting to note the 
limits of the irritability after death in nerves of different 



94: NERVOUS SYSTEM. 

properties and the differences in the manner of its disappear- 
ance. The woorara-poison, a very curious agent prepared 
by the South- American Indians, has the remarkable prop- 
erty of paralyzing .the motor nerves, leaving the nerves of 
sensation intact. This fact has been demonstrated by Ber- 
nard and others by very curious and ingenious experiments. 
The poison, like those of animal origin, acts most vigorously 
xfter introduction under the skin or absorption from wounds, 
and produces no toxic effects when taken into the stomach, 
except when introduced in large quantity in fasting animals. 
Under the influence of this agent, an animal dies with com- 
plete paralysis of the motor system, presenting, among other 
phenomena, arrest of respiration. Most of the varieties of 
the poison affect only the motor nerves, and do not influence 
the action of the heart ; and in animals brought completely 
under its influence, artificial respiration will enable the heart 
to continue its action, and, in some instances, if this be per- 
sisted in, recovery will take place. 

The fact that the woorara-poison affects the motor nerves 
only has been experimentally illustrated by Bernard, tak- 
ing advantage of the reflex functions of the spinal cord to 
show the persistence of the irritability of the sensory nerves. 
The most striking of these experiments is the following : A 
frog is prepared by exposing the nerves in the lumbar re- 
gion, and then isolating the posterior extremities by apply- 
ing a strong ligature, including the aorta and all the parts 
except the nerves ; so that, practically, the only communica- 
tion between the posterior extremities and the body is by 
the nerves. It is evident, therefore, that if the poison be 
introduced under the skin of the body, acting, as it does, 
through the blood, it will affect all parts except the poste- 
rior extremities ; for the poison acts from the periphery to 
the centres, and must circulate in the parts to which the 
motor nerves are distributed. If the posterior extremities 
be now irritated, the impression is conveyed to the spinal 
cord through the sensory filaments of the lumbar nerves, 



NERVOUS IRRITABILITY. 95 

which are intact ; this gives rise to a stimulus, which is re- 
flected back through the motor filaments of the same nerve, 
and the ordinary reflex movements are observed in the 
posterior extremities. This is to be expected, inasmuch 
as the posterior extremities arc removed from the influence 
of the poison. If the anterior extremities, which are com- 
pletely under the influence of the poison, be now irritated, 
no movements are observed in these parts, but they take 
place, as before, in the posterior extremities. The mechan- 
ism of this action is easily understood. Reflex phenomena, 
consisting in the movements of muscles, may be manifested 
throughout the entire system, following irritation of a single 
part. An impression made upon the surface is conveyed to 
the spinal cord, and, if this be sufficiently powerful, motor 
stimulus may be sent through all of the anterior roots com- 
ing from the cord. The impression made upon the anterior, 
or poisoned extremities, is conveyed by the sensory fila- 
ments to the cord and is transmitted to the posterior ex- 
tremities through their motor nerves, which are intact. The 
fact of the transmission of the impression from the anterior 
extremities to the cord shows that the poison does not affect 
the sensory system. 1 

In the same way that the woorara-poison paralyzes the 
motor nerves, leaving the sensory system intact, other 
agents, as anaesthetics, will abolish the sensibility of the 
nerves without affecting the motor filaments. This well- 
known fact has also been experimentally illustrated by Ber- 
nard. 3 

As we have already intimated in another connection, the 
nerves soon lose their irritability after they have been sepa- 
rated from the centres. 3 This loss of conducting power is 

1 BERNARD, Lemons sur la phy&iologie et la pathologie du systeme nerveuz, Paris, 
1858, tome i., p. 203, et seq. /-and, Lefons sur les proprietes des tissiis vivants Y 
Paris, 1866, p. 254, et seq, 

2 BERNARD, TJitorie physiologique de Tanesthesle. Rente dt& cows scienti- 
figues, Paris, 1868-'69, tome vi., p. 383. 

3 See page 80. 

107 



96 NERVOUS SYSTEM. 

attended with important structural changes in the nerve- 
fibres. The tubes lose their normal appearance, and the 
medullary matter becomes opaque and coagulates in large 
drops. The axis-cylinder is not so much modified in struct- 
ure, but it certainly loses its characteristic physiological 
properties. 

The excitability of the motor nerves, according to the 
observations of Longet, disappears in about four days after 
resection. 1 Of course, in experiments upon this point, it is 
necessary to excise a portion of the nerve to prevent reunion 
of the divided extremities ; but when this is done, after the 
fourth day, galvanization of the nerve will produce no con- 
traction in the muscles, though the latter retain their con- 
tractility, as may be shown by the application of direct irri- 
tation. This loss of irritability is gradual, and continues, 
whether the nerve be exposed and stimulated from time to 
time or be left to itself ; and the loss of excitability pro- 
gresses from the centres to the periphery. In the researches 
of Longet on this subject, it was found that the lower por- 
tion of the peduncles of the brain lost their irritability first ; 
then the anterior columns of the cord, then the motor roots 
of the nerves, and, last of all, the branches of the nerves 
near their termination in the muscles. 

The sensibility of the sensory nerves disappears from 
the periphery to the centres, as is shown in dying animals 
and in experiments with ansesthetics. The sensibility is 
lost, first in the terminal branches of the nerves, next in the 
trunks and in the posterior roots of the spinal nerves, and 
so on to the centres. 2 "We have often illustrated this fact in 
experiments upon the roots of the spinal nerves and in sec- 
tion of the large root of the fifth pair within the cranial 
cavity. "When an animal is brought so completely under 
,the influence of ether that the operation of opening the spi- 
nal canal may be performed without inflicting the slightest 

1 LONGET, Trade de physiologic, Paris, 1869, tome iii., p. 171. 

2 LONfiET, Op. tit., p. 175. 



NERVE-FORCE. 97 

pain, the posterior roots will be found to be distinctly sen- 
sible. TTe have lately been in the habit, in class-demonstra- 
tions, of dividing the fifth pair in the cranium without using 
an anaesthetic, as the operation is instantaneous and the 
effects are much more striking in this way ; but when we 
have used an anaesthetic, we could never push the effects 
sufficiently to abolish the sensibility of the root of the nerve. 
In an animal brought so fully under the influence of ether 
that the conjunctiva, supplied with branches of the fifth, 
had become absolutely insensible, the instant the instrument 
touched the root of the nerve in the cranium, there were 
evidences of acute pain. Nothing could more strikingly 
illustrate the mode of disappearance of the sensibility of the 
nerves from the periphery to the centres. 

The nervous irritability may be momentarily destroyed 
by severe shock in killing an animal. This is sometimes 
illustrated in preparing frogs for experiments on the nerves ; 
the shock of killing the frog by decapitation, tearing off 
the skin, etc., abolishing the irritability of the nerves for 
the moment. The observations of Longet and Masson have 
shown, also, that a galvanic shock sufficiently powerful to 
destroy life abolishes instantly the excitability of the motor 



Nerve-Force. The so-called nervous irritability, artifi- 
cially manifested by the application of a stimulus directly to 
the nerve-tissue, enables the nerves to conduct from the cen- 
tres to the periphery a force which is generated in the gray 
substance. This we may call the nerve-force. Its produc- 
tion is one of the most remarkable of the phenomena of 
life ; and its essence, or the exact mechanism of its genera- 
tion, is one of the problems that has thus far eluded the 
investigations of physiologists. We know, however, that in 
the operations of the nervous system, the nerves serve sim- 
ply as conductors and the nerve-cells generate the nerve- 

1 LONGET, Traite de physiologic, Paris, 1869, tome ii., p. 602. 



98 NERVOUS SYSTEM. 

force. It is evident, also, that nearly all of the so-called 
vital phenomena are more or less influenced and controlled 
through this wonderful agent ; and throughout our study of 
the nervous system, we shall be constantly investigating the 
phenomena attending the operation of nerve -force, while 
compelled to admit our ignorance of its essential nature. 

Non-identity of Nerve-Force with Electricity. When we 
come to study fully the action of electricity upon the nerves, 
we shall see that this is by far the most convenient stimulus 
for exciting the nervous action, and one by which we closely 
imitate the true nerve- force. So great is the similarity, in- 
deed, between some of the phenomena produced by the ap- 
plication of electricity and those attending the physiological 
action of nerves, that some physiologists have regarded the 
nerve-cells as generators of an electric current. This hy- 
pothesis explains the nature of nerve-force, in so far as it 
assimilates it to a force, with the action of which, as artifi- 
cially generated, we are more or less familiar. No one at 
the present day, however, pretends that the nerve-force has 
been demonstrated to be identical with any form of elec- 
tricity ; and the question does not now demand extended 
discussion. 

A series of experiments made by Prevost and Dumas, 
in 1823, are worthy of note as showing the absence of a true 
electric current in nerves in action ; 1 but these have been 
confirmed in later years with apparatus sufficiently delicate 
to settle the question beyond a doubt. The most conclusive 
experiments on this subject are those of Matteucci and Lon- 
get, made upon horses at the veterinary school at Alfort. 
These physiologists exposed the sciatic nerves in 'the living 

1 PREVOST ET! DUMAS, Memoire sur les phenomenes qui accompagnent la con- 
traction de la fibre mu&culaire. Journal de physiologic, Paris, 1823, tome iii., p. 
328. Analogous experiments, with the same results, were made later by Person 
(Sur Thypothese des courans electriques dans les nerfs. Journal de physiologie^ 
Paris, 1830, tome x., p. 216, el seq.). 



RAPIDITY OF NERVOUS CONDUCTION. 99 

animal, and, when there was evidently a conduction in both 
directions, as evinced by pain and muscular action, failed to 
detect the slightest evidence of an electric current with the 
most delicate galvanometer that could be constructed. The 
fact of the absence of a galvanic current in nerves during 
their physiological action was even more strikingly illus- 
trated by Matteucci, who demonstrated, in the electric eel, 
that although the electric discharges from the peculiar or- 
gans of this animal were under the control of the nervous 
system, and could be excited by galvanic stimulation of the 
proper nerves immediately after death, no galvanic current 
existed in these nerves during their physiological action. 1 

AVhen we abandon the hypothesis of the identity of 
nerve-force with electricity, we are compelled to admit that 
the agent generated by the nerve-centres is sui generis, and 
not to be compared with any force generated outside of liv- 
ing organisms or artificially produced by direct stimulation 
of the nerves ; but we admit, nevertheless, the fact that 
electricity may be generated by animals, as the electric fish- 
es, and that electric currents exist in different anatomical 
elements of the living body, including the nerves, under cer- 
tain conditions. Our study of the nerve-force, then, leaving 
its essential nature unexplained, is mainly confined to a de- 
scription of its attending phenomena. 

Rapidity of Nervous Conduction. Until within the last 
few years, it has been assumed by many that the rapidity of 
nervous conduction was one of those problems in human 
physiology that could never be satisfactorily resolved ; and 
those who have investigated the history of this question, 
which dates from before the time of Haller, have often 
quoted the words of Miiller, who says, in his great wo^k 
on the " Elements of Physiology," that " we shall probably 
never attain the power of measuring the velocity of nervous 
action ; for we have not the opportunity of comparing its 

1 LONGET, Traite de physiologic, Paris, 1869, tome ill, p. 276, et seq. 



100 NERVOUS SYSTEM. 

propagation through immense space, as we ha V T C in the case 
of light." 1 

The conjectures of writers before Haller were based upon 
the supposed similarity between nervous conduction and the 
passage of electricity ; but Haller formed an estimate of the 
rapidity of nervous conduction by ascertaining the number 
of letters he was able to pronounce in one minute in read- 
ing aloud from the " JSneid." a Calculating then the dis- 
tance of the nervous course from the brain to the muscles, 
he estimated that the nerve-force moved at the rate of about 
one hundred and fifty feet in a second. 3 This estimate is 
not very far from the truth ; at all events, it gives an idea 
of the relative slowness of nerve-conduction as compared 
with electricity or light, which travels at the rate of many 
hundred millions of feet in a second. 

The first rigorous estimates of the velocity of the nerve- 
current were made in 1850, by Helmholtz, 4 and were applied 
to the motor nerves. The important and interesting re- 
sults of these experiments were arrived at by an ingenious 
application of the graphic method, which has since been so 
largely improved and extended by Marey, and their accuracy 
was rendered possible by the exceedingly delicate chrono- 
metric apparatus which has been devised within the last 
few years. 

It is unnecessary to describe fully the exact methods 
employed by Helmholtz and those who immediately followed 
in his investigations ; suffice it to say that this distinguished 
physiologist and physicist constructed apparatus which, 
though somewhat complex, was so accurate as to leave no 
doubt as to the reliability of his results. Taking into 
account all of the disturbing conditions, and allowing for the 

1 MULLER, Elements of Physiology, London, 1840, vol. i., p. 729. 

* HALLER, Elementa Physiologice, Lausannse, tomus iv., p. 483. 

8 Op. tit., tomus iv., p. 373. 

4 HELMHOLTZ, Note sur la vitesse de propagation de Tagent nerveux dans les 
nerfs rachidiem. Comptes rendus, Paris, 1850, tome xxx., p. 204, and, 1851, 
tome xxxiii., p. 262. 



SAPIDITY OF NERVOUS CONDUCTION. 101 

interval of pose, or the length of time between the excitation 
of a muscle and the commencement of its contraction, 1 he esti- 
mated the rapidity of conduction in the motor nerves of the 
frog at about eighty-five feet per second. 9 The results ob- 
tained by Marey upon frogs give a much slower rate of 
nervous conduction. These were followed, however, by the 
observations of Helmholtz and Baxt on the human subject, 
which are, of course, the most interesting of all. 

The process devised by Marey is beautifully simple. He 
employed, to estimate small fractions of a second, a cylinder 
graduated in the following manner: An ordinary tuning- 
fork, vibrating, say, five hundred times per second, is so 
arranged that a point connected with one of its arms is made 
to play against a strip of blackened paper. As the paper 
remains stationary, the point makes but a single mark ; but 
when the paper moves, as the point vibrates, a line is pro- 
duced with regular curves, every curve representing T J 7 
of a second. Now, if a lever be attached to a muscle, and 
be so arranged as to mark upon the paper, moving at the 
same rate, the instant when contraction takes place, it is evi- 
dent that the interval between two contractions produced 
by stimulating the nerve at different points of its course will 
be most accurately indicated ; and if the length of the nerve 
between the two points of stimulation be known, the differ- 
ence in time will represent the rate of nervous conduction. 3 

In experiments upon frogs, the leg is prepared by cutting 
away the muscles and bone of the thigh, leaving the nerve 
attached. The lever is then applied to the muscles of the 
leg and the stimulation is applied successively at two points 
in the nerve, the distance between them being carefully 
measured. The results obtained in this way showed a rate 

1 See vol. iii., Movements, p. 472. 

8 Comptes rendus, Paris, 1851, tome xxxiii., p. 262. 

3 MAREY, Du mouvement dans les fonctions de la vie. Revue des cours scien- 
tijiques, Paris, 1865-'66, tome iii., p. 346, et seq.; and, Du mouvemenf, etc., Paris, 
1868, p. 410, et seq. 



102 NEKVOUS SYSTEM. 

of conduction of from thirty-six to forty-six feet per second ; 
but these are not regarded by Marey as invalidating the 
estimates by Helmholtz, in view of the various conditions by 
which the rapidity of conduction is modified. 1 

Employing the myograph of Marey, Baxt, in the labora- 
tory of Helmholtz, has succeeded in measuring the rate of 
nervous conduction in the human subject. In these experi- 
ments, the swelling of the muscle during contraction was 
limited by enclosing the arm in a plaster-mould, and noting 
the contraction through a small opening. By then exciting 
the contraction by stimulating the radial nerve successively 
at different distances from the muscle, the estimate was 
made. The rate in the human subject was thus estimated at 
one hundred and eleven feet per second. 2 The latest experi- 
ments on this subject by Helmholtz and Baxt, in which great 
care was taken in the adjustment of the apparatus, showed a 
mean of rapidity for the motor nerves, in man, of about two 
hundred and fifty-four feet per second. These observations 
were made in the summer of 1869 ; and the difference in the 
results is in part explained by the fact, which was ascertained 
experimentally at that time, that a high temperature in- 
creases, and a diminished temperature retards the velocity 
of nervous conduction. 3 It has been further shown by Munk, 
that the rate of conduction is different in .different portions 
of the nervous trunk ; the rapidity progressively increasing 
as the nerve approaches its termination. 4 

Helmholtz, Du Bois-Reymond, B Marey, and others, have 

1 MAREY, Du mouvement, etc., Paris, 1868, p. 433. 

2 BAXT, Versuche uber die Fortpflanzungsgeschwindigkeit der Reizung in den 
motorischen Nerven des Menschen. Monatsbericlde der kdniglich Preussischen 
Akademie der Wissenschaften zu Berlin, aus dem Jahre, 1867, Berlin, 1868, S. 233. 

3 HELMHOLTZ UND BAXT, Fortpjlanzungsgeschwindigkeit der Erregung in 
Bewegungsnerven. Der Naturforscher, Berlin, 1870, Bd. Hi., S. 230. 

4 MUNK, Untersuchunaen uber die Zeitung der Erregung in Nerven. A rchiv 
fur Anatomie, Physiologic, und wissenschaftliche Medecin, Lsipzig, 1864, S. 798, 
et seq. 

6 Du BOIS-REYMOND, Vitesse de la transmission de la volonte et de la sensation d 
iravers les nerfs. Revue des cours scientifiques, Paris, 1866-'67, tome iv., D. 37 



RAPIDITY OF NERVOUS CONDUCTION. 103 

noted certain conditions which modify the rate of nervous 
conduction. One of the most prominent of these, first ob- 
served by Helrnholtz, is due to modifications in temperature. 
By a reduction of temperature, in the frog at least, the rate 
is very much reduced ; and at 32 it is not more than one- 
tenth as rapid as at 60 or TO . Marey has also noted that 
the rate is sensibly reduced by fa'tigue of the muscles. 1 

The same principle which has led to the determination of 
the rate of conduction in motor nerves; viz., an estimation 
of the difference in time of the passage of a stimulus applied 
to a nerve at two points situated at a known distance from 
each other, has been applied to the conduction of sensations. 
Hirsch is quoted as having made the first attempt id resolve 
this question, in 1851. a He employed the delicate chrono- 
metric instruments used in astronomy, and noted the dif- 
ference in time between the appreciation of an impression 
made upon a part of the body far removed from the brain, 
as the toe, and an impression made upon the cheek. This 
process admitted of the rough estimate of about one hundred 
and eleven feet per second ; an estimate agreeing remarkably 
with that of Eaxt for the motor nerves. The later and more 
elaborate researches of Schelske show a rapidity of conduction 
by the sensory nerves of about ninety-seven feet per second. 3 

Attempts have been made by Helmholtz, Du Bois-Rey- 
mond, 4 Marey, 5 Bonders, 6 and others, to estimate the dura- 

1 MAREY, Du mouvement dans lesfonctions de la vie, Paris, 1868, p. 433. 

2 LOXGET, Traite de physiologic, Paris, 1869, tome in., p. 291. 

3 SCHELSKE, Nene Messungen der Fortpflanzungsgeschwindigkeit des Reizes in 
den menschlichfn Nerven. Archiv fur Anatomic, Physiologic und iribsenchaftUcht 
M'.'l.rin, Leipzig, 1864, S. 172. 

4 Du BOIS-REYMOND, On the Time required for the Transmission of Volition 
and Sensation through the Nerves. A Lecture given at. the Royal Institution. 
BEXCE JOXES, Croonian Lectures on Matter and Force, London, 1868, Appendix 
L, p. 97, et seq. ; and, Revue des cours scientijiqaes, Paris, 1866-'67, tome iv., p. 
39, et seq. 

5 MAREY, Du mouvement dans lesfonetions de la vie, Paris, 1868, p. 442. 

6 DOXDERS, Velocity of Cerebral Functions. The Quarterly Journal of Psy- 
chological Medicine, New York, 1869, vol. iii., p. 763, et seq. 



104: NERVOUS SYSTEM 

tion of acts involving the central nervous system, as the 
reflex phenomena of the spinal cord or the operations of the 
cerebral hemispheres. These have been partially successful, 
or, at least, they have shown that the reflex and cerebral 
acts require a distinctly appreciable period of time. This, 
in itself, is an important fact ; though the duration of these 
acts has not yet been measured with all the accuracy that 
could be desired. As the general result of experiments upon 
these points, it is found that the reflex action of the spinal 
cord occupies more than twelve times the period required 
for the transmission of stimulus or impressions through the 
nerves. 1 Donders found, in experiments on his own person, 
that an act of volition required one-twenty-eighth of a sec- 
ond, and one of simple distinction or recognition of an im- 
pression, one-twenty-fifth of a second. 2 These estimates, 
however, are merely approximative ; and until they attain 
greater certainty, it is unnecessary to describe in detail the 
apparatus employed. 

The general result of the various observations we have 
detailed upon the rate of nervous conduction as applied to 
the human subject is, in the first place, that this can be 
measured with tolerable accuracy.; second, that it is in no 
wise to be compared with the rate of conduction of light or 
electricity ; and, finally, that the rate in the human subject 
is essentially the same in the motor and sensory nerves, be- 
ing, according to the most reliable estimates, about one hun- 
dred and eleven feet per second. 

Elevation of Temperature in Nerves during their Func- 
tional Activity. There is little to note under this head, ex- 
cept the fact that functional activity of the nerves produces 
an amount of elevation to temperature in their substance 
which can be distinctly demonstrated by sufficiently delicate 
thermometric apparatus. Under the head of animal heat, 
in another volume, we have given the results of recent ob- 

1 Du BOIS-REYMOND, loc. cit. 9 DONDERS, be. cit. 



ACTION OF ELECTRICITY UPOX THE XERVES. 105 

servations by Lombard, showing an elevation in the tem- 
perature of the head during mental exertion. 1 The same 
facts have lately been observed by Schiff, 2 who has also 
shown a slight elevation of temperature in nerves during 
the conduction of an artificial stimulus. 8 



Action of Electricity upon the Nerves. A great deal has 
been written upon the effects of electricity upon the nervous 
system, and facts elicited by experiments upon this subject 
are highly important in their bearing on physiology and 
pathology. Still, there are numerous observations upon 
this subject which have but little importance, in a purely 
physiological sense, except that they are curious and inter- 
esting. These we do not propose to discuss elaborately ; 
but shall confine ourselves chiefiy to those points which bear 
directly upon our knowledge of the properties and functions 
of the nerves. 

The first important fact to which we have already al- 
luded is, that electricity is the best means that we have of 
artificially exciting the nerves. Using electricity, we can 
regulate with exquisite nicety the degree of stimulation ; 
we can excite the nerves long after they have ceased to re- 
spond to mechanical or chemical irritation ; the effects of 
different currents can be noted ; and, finally, this mode of 
stimulation produces a peculiar and interesting condition of 
the parts of the nerve not included between the poles of the 
battery. For these reasons, it seems proper to devote some 
consideration, in this connection, to the effects of the appli- 
cation of this agent to the nerves. 

So long as the nerves retain their irritability, they will 
respond to an electrical stimulus. Experiments may be 
made upon the exposed nerves in living animals or in ani- 

1 See vol. in., Animal Heat, p. 415. 

2 MORITZ SCHIFF, Recherche* sur Vechauffemeni des nerfs et des centres nerveux 
it la suite des irritations semorielles et sensitives. Archives de physiologic, Paris, 
1870, tome iii., p. 5, et seq. 

3 Ibid., 1869, tome ii., pp. 157 and 330. 



106 NERVOUS SYSTEM. 

mals just killed ; and, of all classes, the cold-blooded animals 
present the most favorable conditions, an account of the 
persistence of nervous and muscular irritability for a consid- 
erable time after death. Experimenters most commonly use 
frogs, on account of the long persistence of the irritability 
of their tissues and the facility with which certain portions 
of the nervous system can be exposed. For ordinary experi- 
ments upon the nervous conduction, the parts are prepared 
by detaching, the posterior extremities, removing the skin, 
and cutting away the bone and muscles of the thigh, so as 
to leave the leg with the sciatic nerve attached. A frog's 
leg thus isolated presents a nervous trunk one or two inches 
in length, attached to the muscles, which will respond to the 
slightest stimulus. It is by experiments made upon frogs 
prepared in this way that most of the important facts rela- 
tive to the action of electricity upon the nervous system 
have been developed. 

It is evident that the galvanic current may be applied to 
a nerve so that the direction may, in the one case, follow the 
course of the nerve, that is, from the centre to the periph- 
ery, and, in the other, be opposite to the course of the nerve. 
These currents have been called respectively the direct, or 
descending, and the inverse, or ascending. 1 "When the posi- 
tive pole (the copper) is placed nearer the origin of the 
nerve, and the negative pole (the zinc) below this point in 
the course of the nerve, the galvanic current follows the 
normal direction of the motor conduction, and this is called 
the direct current. When the poles are reversed, and the 
direction of the galvanic current is from the periphery 
toward the centre, it is called the inverse current. It will 
be convenient to speak of these two currents respectively as 
direct and inverse, in detailing experiments upon the action 
of electricity upon the nerves. 

The points to be noted with regard to the effects of the 

1 The direct current is sometimes called centrifugal, and the inverse, centrip- 
etal. 



ACTION OF ELECTRICITY UTON THE NERVES. 107 

application of electricity to an exposed nerve are the action 
of constant currents of different degrees of intensity, the 
phenomena observed on making and breaking the circuit, 
and the effects of an interrupted current. 

During the passage of a feeble constant current through 
an exposed nerve, whatever be its direction, there are no 
convulsive movements and no evidences of pain. This fact 
has long been recognized by physiologists, who at first 
limited the effects of electricity upon the nerves to two 
periods, one at the making of the circuit and the other at its 
interruption. We shall see, however, that the passage of 
electricity through a portion of a nervous trunk produces a 
peculiar condition in parts of the nerve not included between 
the poles of the battery, described by Du Bois-Reymond 
under the name of electrotonus ; but the fact that neither 
motion nor sensation is excited in a mixed nerve .during the 
actual passage of a feeble constant current is not invalidated. 

If a sufficiently powerful constant current be passed 
through a nerve, disorganization of its tissue takes place, and 
the nerve finally loses its excitability, as it does when 
bruised, ligatured, or when its structure is destroyed in any 
other way. 1 It was thought by Galvani, and the idea has 
been adopted by Matteucci, Guerard, and Longet, 9 that a 
current directed exactly across a nerve, so as to pass at right 
angles to its fibres, does not give rise to muscular contrac- 
tion ; but it is doubtful whether this can be accepted as a 
demonstrated fact. Chauveau has found that a transverse 
current passed through the exposed facial nerve of a horse 
produces well-marked muscular action. He is of the opinion 
that the experiments of Galvani and his followers, made upon 
frogs, are faulty, inasmuch as the nerve is so small that but 
little if any of the galvanic current passes through its sub- 
stance, being conducted from one pole to the other through 

1 BERNARD, Lerons sur la physiologic et la pathologie dusysteme nerveux, Paris, 
1858, tome i.,p. 162. 

8 LOXGET, Traile de physiologic, Paris, 1869, tome iii., p. 193. 



108 NEKVOUS SYSTEM. 

the surrounding moisture, which, in his own experiments, 
was carefully removed. 1 Longet has noted that pain is pro- 
duced by the passage of a transverse current through a sen- 
sitive trunk, and that the pain does not seem to be increased 
when the poles are separated and the current thus is sent 
through a portion of the length of the nerve. 2 

All who have experimented upon the action of galvanism 
upon the mixed nerves have noted the fact alluded to above, 
that the phenomena of contraction are manifested only on 
closing or breaking the circuit. Take, for example, a frog's 
leg prepared with the nerve attached ; place one pole of a 
feeble galvanic apparatus on the nerve and then make the 
connection, including a portion of the nerve in the circuit, 
and usually, a contraction of the muscles will occur when the 
circuit is closed, the limb will be quiet during the passage of 
the current, and another contraction will take place when 
the circuit is broken. "When the parts are freshly prepared, 
the contractions take place as described,, whatever be the 
direction of the current. 3 After a time, however, the ner- 
vous irritability becomes somewhat enfeebled, and then it is 
observed that the contraction occurs in some instances when 
the circuit is closed, and in others when the circuit is broken. 
The differences in the time of appearance of these phenom- 
ena have been found to depend upon the direction of the 
current, and may be formularized as follows : 

If the sciatic nerve attached to the leg of a frog, prepared 

1 CHAUVEAU, Effets physiologiques de Velectridte. Journal de la physiologic, 
Paris, 1860, tome Hi., p. 298. 

2 LONGET, loc. cit., p. 201. 

3 A form of galvanic apparatus which we have long used and found very 
convenient for these experiments is essentially the one described by Bernard 
(Systeme nerveux, Paris, 1858, tome i., p. 144). It consists simply of alternate 
copper and zinc wires wound around a piece of wood bent in the form of a 
horseshoe and terminating in two platinum points representing the positive and 
negative poles. This forms a sort of electric forceps, about eight inches long, 
which, when moistened with water slightly acidulated with acetic acid, will give 
a current of about the strength required for most of the experiments detailed 
above. 



ACTIOX OF ELECTRICITY UPOX THE NERVES. 100 

In the usual way for such experiments, be subjected to a feeble 
galvanic current, there is a time when muscular contraction 
takes place only at the instant when the circuit is made ; no 
contraction occurring when the circuit is Broken ; and this 
occurs only with the direct current ; i. e., when the current 
flows toward the periphery, the positive pole being above, 
and the negative below. If the poles be reversed, so that 
the galvanic current flows from the periphery toward the 
centres the inverse current contraction of the muscles 
occurs only when the circuit is broken and none takes place 
when the circuit is closed. 

These phenomena are distinct after the irritability of the 
parts has become somewhat diminished by exposure or by 
electric stimulation of the nerve, but they may occur in per- 
fectly fresh parts, when the galvanic current is very feeble. 
Usually, when the nervous irritability is at its height, con- 
tractions occur both on closing and breaking the circuit ; but 
they are more powerful on closing the circuit, for the direct 
current, and on breaking the circuit, for the inverse current. 
This fact has been noted by all experimenters since the time 
of Hitter, by whom the essential characters of these phenom- 
ena were first described. 1 Hitter was in error in supposing 
an antagonistic action of the flexor and extensor muscles 
excited by making the circuit with the direct, and breaking 
the circuit with the inverse current ; but most of his descrip- 
tions of the effects of different currents are remarkably 
accurate and have been fully confirmed by late observers. 

A very simple experiment made by Matteucci strikingly 
illustrates the contrasted action of the direct and the inverse 
current. The posterior extremities of a frog are prepared 
so as to leave the nerves on the two sides connected together 
by a portion of the spinal column. The legs are then placed 
each one in a wineglass of water, and a feeble galvanic cur- 
rent is passed from one glass to the other. It is evident 

1 RITTER, Beytrage zurndhern Kenntniss des Gralvanismiis, Jena, 1805, Bd. ii., 
drittes, viertes und letztes Stuck, S. 132, et seq. 



110 NERVOTJS SYSTEM. 

that, with this arrangement, the current will pass through 
both nerves, being direct for the one and inverse for the 
other. In this case, if the irritability of the nerves be not 
too intense, ther'e will be a contraction in the leg in which 
tho current is direct at the time of making the circuit, while 
the other leg will contract when the circuit is broken. 1 This 
experiment has been modified by Chauveau, and applied to 
the two facial nerves in a living horse. A Leyden jar is 
very feebly charged with electricity, and the two facials are 
exposed. The current is then passed instantaneously through 
both the nerves, which gives but a single stimulus and that 
corresponds to the time of making the circuit with the con- 
stant current. In this experiment, the current is direc't for 
one nerve and inverse for the other, and contraction takes 
place only in those muscles supplied with the nerve for 
which the current is direct. 3 

The muscular contraction produced by galvanic stimula- 
tion of the nerve is more vigorous the greater the extent of 
the nerve included between the poles of the battery. This 
fact has long been observed, and its accuracy is easily veri- 
fied. It would naturally be expected that the greater the 
amount of stimulation the more marked would be the mus- 
cular action ; and the stimulation seems to be increased in 
proportion to the extent of nerve through which the gal- 
vanic current is made to pass. 

The irritability of a nerve, it is well known, may be ex- 
hausted by the repeated application of electricity, whatever 
be the direction of the current, and is more or less com- 
pletely restored by repose. It is a curious fact, in this con- 
nection, that when the irritability of a nerve has been ex- 
hausted for the direct current, it will respond to the inverse 
current, and vice versa / and it is even more remarkable that 
after the irritability has been exhausted by the direct cur- 

1 MATTEUCCI, Lemons sur les phenomena physiques des corps vivants, Paris, 
1847, p. 233. 

8 CHAUVEAU, op. cit. Journal de la physiologic, Paris, 1860, tome iii., p. 67. 



ACTION OF ELECTRICITY UPON THE NERVES. Ill 

rent, it is restored more promptly by stimulation with the 
inverse current than by absolute repose, and vice versa. 
This phenomenon, observed by Yolta, is sometimes known 
as " voltaic alternation." * It is very strikingly illustrated in 
frogs prepared as above described, with the two posterior 
extremities, the nerves attached through a portion of the 
spinal cord, placed in vessels of water so tl^at a current may 
be simultaneously passed through both nerves, being 'direct 
for the one and inverse for the other. As we have already 
seen, after a time, contraction occurs only in one leg, for 
which the current is direct, on making the circuit, and in the 
other, only on breaking the circuit. By repeatedly passing 
the current in this way, after a time there will be no con- 
traction in either leg, the irritability of the nerves having 
become exhausted. If the poles of the battery be now re- 
versed, so as to make the inverse current take the place of 
the direct, contractions with making and breaking the cir- 
cuit will again occur. The irritability may again be ex- 
hausted and restored by changing the poles, and this may 
be repeated several times with the same preparation. 

There can be no doubt with regard to the action of the 
direct and inverse currents, as above described, applied to 
nerves exclusively motor, as well as to the mixed nerves. In 
the mixed nerves separated from the centres, it is evident 
that the motor elements only are acted upon ; and it would 
be difficult to understand how the action of these currents 
could be different when applied to the anterior roots of the 
spinal nerves. Longet and Matteucci, however, in their 
earlier experiments upon the anterior roots of the spinal 
nerves, observed that contraction of muscles took place on 
breaking the circuit, with the direct current, and on making 
the circuit, with the inverse current ; precisely the opposite 
of the phenomena noted in experiments on the mixed 
nerves ; and Longet proposed from this to draw a distinc- 
tion between the ordinary nerves and those possessed of ex- 

1 LONGET, Traite de physiologic, Paris, 1869, tome ill, p. 199. 
108 



112 NERVOUS SYSTEM. 

clusivel j motor properties. The error in these observations, 
however, was early pointed out by Rousseau, whose experi- 
ments were fully detailed by Bernard before they were pub- 
lished separately. 1 Rousseau found that when galvanism 
was applied to a mixed nerve still connected with its cen- 
tres, two galvanic currents were established ; the one taking 
the shorter course through that portion of the nerve includ- 
ed between the poles of the battery, and the other, called the 
" derived current," taking an opposite direction through the 
nerves and the tissues. It is evident that the derived cur- 
rent would be inverse for the nerve when the shorter cur- 
rent is direct, and vice versa. Now if the extent of nerve 
included between the poles of the battery be short, the de- 
rived current would predominate, and we would seem to 
have contraction with the closure of the inverse and the 
opening of the direct current. This fact was fully demon- 
strated by Rousseau, who devised a little apparatus for neu- 
tralizing the derived current, when the phenomena follow- 
ing the application of the currents to the nerves attached 
were the same as those observed in divided nerves. 2 In 
1859-'60, shortly after these experiments were published, 
we repeated them before a medical class, and have no doubt 
as to the accuracy of the results. The experiments of Rous- 
seau have since been confirmed by Chauveau ; 8 and Mat- 
teucci; 4 in his later publications, acknowledges the error of 
his first observations, though Longet still adheres to his ori- 
ginal deductions. 6 

Induced Muscular Contraction. A curious phenomenon 

1 ROUSSEAU, in BERNARD, Lemons sur la physiologie et la pathologic du systeme 
nerveux, Paris, 1858, tome i., p. 170, et seq. 

2 Loc. dt., p. 181. 

3 CHAUVEAU, Effeis physiologiques de Peledricite. Journal de la physiologie, 
Paris, 1860, tome in., p. 458, et seq. 

4 M ATTEUCCI, Phenomenes physico-chimiques des corps vivants. Revue des cours 
xdentifiques, Paris, 1867-'68, tome v., p. 508. 

6 LONGEI, Traite de physwlogie, Paris, 1869, tome iii., p. 187. 



INDUCED MUSCULAR CONTRACTION. 113 

was discovered by Matteucci, in experimenting upon nervous 
and muscular irritability, which has been called " induced 
muscular contraction." 1 It was found that if the nerve of a 
galvanoscopie frog's leg (the leg prepared with the nerve 
attached in the way already described) be placed in contact 
with the muscles of another leg prepared in the same way, 
galvanization of the nerve giving rise to contraction of the 
muscles with which the nerve of the first leg is in contact 
will induce contraction in the muscles of both. This ex- 
periment may be extended, and contractions may thus be in- 
duced in a series of legs, the nerve of one being in contact 
with the muscles of another. This illustrates the great deli- 
cacy of the galvanoscopie frog's leg, as it will indicate a cur- 
rent due to a single muscular contraction, which does not 
affect an ordinary galvanometer. It is conclusively proved 
that the " induced contraction," as just described, is not due 
to an actual propagation of the galvanic current, but to a 
stimulus produced by the muscular contraction itself, by the 
fact that the same phenomena occur when the first muscular 
contraction is produced by mechanical or chemical excitation 
of the nerve. 

Galvanic Current from the Exterior to ike Cut Surface 
of a Nerve. Before we study certain phenomena presented 
in nerves a portion of which is subjected to the action of a 
constant galvanic current, it is important to note the fact, 
discovered many years ago by Du Bois-Reyrnond, that there 
exists in the nerves, as in the muscles, 8 a galvanic current 
from the exterior to their cut surface. 3 This fact has been 
confirmed by all who have investigated the subject of electro- 
physiology. It has been roughly estimated by Matteucci 
that the nerve-current has from one-eighth to one-tenth the 

1 MATTEUCCI, Lemons sur les phenomenes physiques des corps vivants, Paris, 
1847, p. 288. 

* See vol. i., Movements, p. 476. 

8 Du BOIS-REYMOXD, Untersuchungen uber thlerhcke Ekklricitdt, Berlin, 1849, 
S. 251, ft seq. 



114 NERVOUS SYSTEM. 

intensity of the muscular current. 1 The existence of the 
nerve-current has, as far as we know, no more physiological 
significance than the analogous fact observed in the muscular 
tissue. It is presented in nerves removed from the body, and 
has no relation to their functional activity, whether in nor- 
mal action or excited by artificial stimulation. 

Effects of a Constant Galvanic Current upon the Nervous 
Irritability. Aside from the disorganizing effect upon the 
nerves of a powerful constant current, which is due solely 
to decomposition of their substance, a feeble current has been 
found to exert an important influence upon the nervous 
irritability, according to the direction in which the current 
is passed. The law in accordance with which this influence 
is exerted .is stated by Matteucci as follows : 

" A continued electric current passed through a mixed 
nerve, the crural or the lumbar, for example, modifies the 
excitability of the nerve in a very different manner, accord- 
ing to its direction. The excitability is enfeebled by the 
passage of the direct current, and, on the contrary, it is pre- 
served and augmented, at least within certain limits, by the 
inverse current. The time necessary in order that the cur- 
rent shall produce this modification is proportionate to the 
degree of excitability of the nerve and in inverse ratio to the 
intensity of the current. After the breaking of the circuit, 
the modification of the nerve tends to cease at a period that 
is short in proportion as the excitability of the nerve is great 
and the intensity of the current is feeble. This proposition 
explains the difference in the electro-physiological effects of 
the continued current according to its direction, the well- 
known phenomenon of voltaic alternations, and the pe- 
riods discovered and specially studied by Marianini and 
JSTobili." 3 

This law has been carefully studied and formularized, as 
above, by Matteucci, but its discovery is attributed by physi- 

1 MATTEUCCI, Cours tfehctro-physiologie, Paris, 1858, p. 122. 2 Ibid., p. 30 



ELECTKOTONTJS. 115 

ological writers to Pfaff. 1 After a time, varying with the 
excitability of the nerve and the intensity of the current, the 
direct current will destroy the nervous irritability, but this 
may be restored by repose, or more quickly by the passage 
of an inverse current. If the inverse current be passed first 
for a few seconds, a contraction follows the breaking of the 
circuit ; and this contraction, within certain limits, is more 
vigorous the longer the current is passed. At the same time, 
the prolonged passage of the inverse current increases the 
excitability of the nerve for any kind of stimulus. When 
the inverse current has been passed through the nerves for 
several hours, breaking of the circuit is followed by very 
violent contraction and a tetanic condition of the muscles, 
enduring for several seconds. 

Electrotorvus, Anelectrotonus, and Catelectrdtonus. 

Many years ago, Du Bois-Keymond discovered the curious 
and interesting fact, that when a constant galvanic current 
is passed through a portion of a freshly-prepared nerve, those 
parts of the nerve not included between the poles are brought 
into a peculiar condition. While in this state, the nerve 
will deflect the needle of a delicate galvanometer and its ex- 
citability is modified. 9 The deflection of the needle, in this 
instance, is not due to the normal nerve-current, for it occurs 
when the galvanometer is applied to the surface of the nerve 
only. It is due to an electric tension of the entire nerve, in- 
duced by the passage of a current through a portion of its 
extent. This condition is called electrotonus. The phe- 
nomena thus produced have been most elaborately studied by 
Pfliiger, who further recognized a peculiar condition of that 
portion of the nerve near the anode, or positive pole, differing 
from the condition of the nerve near the cathode, or negative 
pole. 2s ear the anode,'the excitability of the nerve is dimin- 

1 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 194. 
8 Du BOIS-REYMOND, Utitersuchungen uber thierische Elektricitat, Berlin, 1849, 
Bd ii., S. 289, et seq. 



116 NERVOUS SYSTEM. 

ished, and this condition has been called anelectrotonus/ 
Near the cathode, the excitability is increased, and this con 
dition has been called catelectrotomis. 2 

These varied phenomena have been the subject of ex- 
tended investigation by electro-physiologists ; and 'although 
they are not to be ranked among the physiological properties 
of the nerves, they have considerable pathological and thera- 
peutic importance. It is well known, fur example, that elec- 
tricity is one of the most efficient agents at our command 
for the restoration of the functions of nerves affected with 
disease ; and the constant current has, particularly of late, 
been extensively and successfully used as a therapeutic agent. 
The constant current, in restoring the normal condition of 
nerves, must influence, not only that portion included be- 
tween the poles of the battery, but the entire nerve ; and 
the electrotonic condition, with its modifications, explains 
how this result may be obtained. Undoubtedly the sensory 
nerves are affected as well as the motor, though we have as 
yet but little positive information upon this point. A knowl- 
edge of the fact that the constant current diminishes the ex- 
citability of the nerve near the anode (anelectrotonos) and 
increases it near the cathode (catelectrotonos) may become 
important in determining the direction of the current to be 
' employed in different cases of disease. 

In the present condition of the subject of electro-physi- 
ology, it will be unnecessary to do more than to indicate, as 
clearly and simply as possible, the laws of the phenomena 
attending the passage of a constant current through nerves, 
as far as they have been definitively ascertained. For a most 
lucid exposition of these laws, the physiological student can- 
not do better than to consult a lecture recently published by 
Dr. Rutherford, of Edinburgh. 3 

1 PFLUGER, Untersuchungen uber die Physiologic des Electrotomis, Berlin, 1859, 
8. 277, et seq. 

* Op. cit., S. 186, et seq. 

8 RUTHERFORD, Eledrotonus. Journal of Anatomy and Physiology, Cambridge 
and London, 1868, vol. ii., p. 87, et seq. 



ELECTROTONTTS. 117 

The phenomena of electrotonus are very simple ; and it 
is only when we attempt to construct a theory to account for 
these phenomena that the subject becomes obscure. Sup- 
pose, for example, that a nerve be exposed in a living ani- 
mal, or in one just killed, and a galvanic current be applied 
from a Grove's battery, in which about twelve square inches 
of zinc are exposed to the action of a liquid containing one 
part of ordinary sulphuric acid to eight of water. 1 A deli- 
cate galvanometer applied to the nerve either above or be- 
low the poles will indicate a decided current, much more in- 
tense than the tranquil nerve-current between the exterior 
and the cut surface. This electrotonic condition exists so 
long as the galvanic current is continued ; and, as has been 
shown by Matteucci in operating upon the higher animals 
rabbits, dogs, fowls, and sheep when the galvanic current 
has been sufficiently powerful and prolonged, the electroto- 
nic condition persists for a certain time after the stimulus 
has ceased. 3 As we have seen that the muscular contraction 
following galvanic stimulation of a nerve is powerful in pro- 
portion to the extent of nerve included between the poles 
of the battery, so the electrotonic condition increases in 
intensity with the length of the nerve subjected to the con- 
stant current ; provided, always, that the strength of the 
current be slightly increased to compensate the enfeebling 
action due to the resistance in the increased length of the 
circuit. 3 

^\Ve do not propose to discuss fully the various theories 
that have been advanced in explanation of the phenomena 
of electrotonus. Matteucci has made a series of interesting 
observations upon conductors formed of very fine wires, one 
of platinum and the other of amalgamated zinc, covered with 
cotton thread soaked in a neutral solution of sulphate of 

1 RUTHERFORD, lor. tit. 

8 MATTEUCCI, Origine de Telecirotone des nerfs. Revue des cours stientifique^ 
Paris, 1867-'68, tome v., p. 279. 

MORGAN, Electro-physiology and Therapeutics, Xew York, 1868, p. 495. 



118 NEKVOUS SYSTEM. 

zinc. The experiments were then arranged so as to operate 
first with the platinum wire and afterward with the zinc, by 
passing a galvanic current through a small portion of the 
conductor, in the same way as it is passed through a portion 
of a nerve. He found that in this way he could produce a 
strong electrotonic current in the platinum wire, even at a 
distance of more than three feet from the electrodes, while 
no such current was observed in the zinc. He remarks that 
in the platinum wire " secondary polarities " are produced 
very powerfully and rapidly, while these are not developed in 
the zinc. 1 From these experiments alone, it might seem that 
the phenomena of electrotonus, as described by Du Bois-Rey- 
mond and others, are to be explained entirely by the physi- 
cal properties of the nerves as conductors of electricity ; but 
various observations on the nerves tinder different condi- 
tions have conclusively proven the contrary. All observers 
are agreed that the electrotonic condition is marked in pro- 
portion to the excitability of the nerve, and is either entirely 
absent or extremely feeble in nerves that are dead, or have 
lost their irritability. If a strong ligature be applied to the 
extra-polar portion of the nerve, or if the nerve be divided 
and the cut ends brought in contact with each other, the 
electrotonic condition is either not observed or is very feeble. 
These facts show conclusively that the phenomena of elec- 
trotonus depend upon the physiological integrity of nerves. 
A dead nerve, or one that has been divided or strongly liga- 
tured, may present these phenomena under the stimulation 
of a very powerful current (and then only to a slight degree), 
when the condition depends upon the purely physical prop- 
erties of the nerve as a conductor ; but there is no compari- 
son between these phenomena and those observed in nerves 
that retain their physiological properties. Were it other- 
wise, how could the physiological properties of a diseased 
nerve be restored throughout its whole extent by a constant 
current passed through a restricted portion, when the exci- 

1 Revue dcs court scientifiques, Paris, 1867-'68, tome v., p. 279. 



ELECTROTONTTS. 119 

lability of the nerve is only manifested at the closing or 
opening of the circuit ? ' 

Anelectrotonus and Catelectrotonus. It is interesting to 
note that when a portion of a nerve is subjected to a moder 
ately powerful constant current, the conditions of the extra 
polar portions corresponding to the two poles of the battery 
are entirely different. ]N"ear the positive pole, or anode, the 
excitability of the nerve and the rate of nervous conduction 
are diminished. If, however, we have a galvanometer ap- 
plied to this portion of the nerve, its electromotive power, 
measured by the deflection of the galvanometric needle, is 
increased. On the other hand, near the negative pole, or 
cathode, the excitability of the nerve is increased as well as 
the rate of nervous conduction ; but the electromotive power 
is diminished. The above is laid down by Rutherford, as 
the law of electrotonus. 8 These facts, at least so far as they 
relate to the increase of the excitability of the nerve near 
the cathode and its diminution near the anode, are partial- 
ly explained by Matteucci upon purely physical principles, 
depending upon - the electrolytic action of the current, as is 
shown by the following experiment : 

Two cups are filled, the one with a very feeble alkaline 
solution, and the other with an equally weak acid fluid. A 
number of galvanoscopic frogs' legs are then rapidly pre- 
pared, of which one-half the number is plunged in the alka- 
line and one-half in the acid fluid, for from thirty seconds 
to one or two minutes. The parts are then removed from 
the liquids, and are carefully washed and dried in bibulous 
paper. By touching the nerves with a strong solution of 

1 It is necessary to note, in this connection, that Matteucci (Joe. cit.) found 
that the electrotonic condition in the platinum wire covered with moistened 
cotton was affected by a strong ligature in nearly the same way as a living nerve, 
when, of course, " the alteration consists principally in the solution of continu- 
ity thus produced in the moist covering of the metallic thread." 

2 RUTHERFORD, Electrotonus. Journal of Anatomy and Physiology, Cambridge 
and London, 1868, vol. ii., p. 98. 



120 NERVOUS SYSTEM. 

common salt, which is a powerful excitant for the nervous 
irritability, the nerves that had been exposed to the alkaline 
solution produced more powerful and prompt contractions 
than those exposed to the acid. Now the electrolytic action 
of a constant current tends to the accumulation of hydrogen 
and an alkali near the cathode, and oxygen and an acid near 
the anode ; and by this, Matteucci explains the increase of 
excitability in catelectrotonus and the diminished excita- 
bility in anelectrotonus. 1 As regards this question, we have 
only to say, as in the case of general electrotonus, that the 
conditions are susceptible of a partial explanation on purely 
physical grounds ; but precisely how far the unexplained 
physiological properties of the nerves are involved, it is im- 
possible to say. 

Neutral Point. The anelectro tonic condition, on the 
one hand, and the catelectrotonic condition at the other 
pole of the battery, are marked in extra-polar portions of 
the nerve, and are to be recognized as well in that portion 
through which the current is passing; but between the 
poles, is a point where these conditions .meet, as it were, 
and where the excitability is unchanged. This has been 
called the neutral point. When the galvanic current is of 
moderate strength, this neutral point is about half-way be- 
tween the poles. " When a weak current is used, the neu- 
tral point approaches the positive pole, while in a strong 
current, it approaches the negative pole. In other words, in 
a weak current the negative pole rules over a wider territory 
than the positive pole, whereas in a strong current the posi- 
tive pole prevails." a 

Negative Variation. There remains one curious phe- 
nomenon, discovered by Du Bois-Beymond, which depends 

1 MATTEUCCI, PMnomenes physico-chimiques des corps vivants. R?vue des 
cours scientifigues, Paris, 1867-'68, tome v., p. 579. 
8 RUTHERFORD, loc. cit., p. 92. 



ELECTROTO2OJS. 121 

upon the action of a rapidly-interrupted current applied to 
an excitable nerve. If a galvanometer be applied to a liv- 
ing nerve so as to indicate by its deviation the normal, or 
tranquil nerve-current, a rapidly-interrupted current of elec- 
tricity passed through a portion of the nerve, it is well 
known, produces a tetanic condition of the muscles. If we 
now watch the needle of the galvanometer, it will be ob- 
served to retrograde, and will finally return to zero,, indi- 
cating that the proper nerve-current has been overcome. 
This will be observed to a slight degree under the influence 
of mechanical or chemical stimulation of the nerve, the 
proper nerve-current being diminished, but generally not 
abolished. This variation of the needle under the influence 
of the tetanic condition has been called negative variation. 1 
We do not yet know that it has any important physiological 
or pathological significance. 

1 Du BOIS-REYMOXD, Untersuchungen uber thierische Ekktridtat, Berlin, 1849, 
Bd. il, S. 425, et seq. 



CHAPTEE IV. 

SPINAL NERVES MOTOR NERVES OF THE EYEBALL. 

Special nerves coming from the spinal cord Cranial nerves Anatomical classi- 
fication Physiological classification Motor oculi communis (third nerve) 
Physiological anatomy Properties and functions Influence upon cer- 
tain muscles of the eyeball Action of the inferior oblique muscle Influ- 
ence upon the movements of the iris Patheticus, or trochlearis (fourth 
nerve) Physiological anatomy Properties and function Action of the 
superior oblique muscle Motor oculi externus, or abducens (sixth nerve) 
Physiological anatomy Properties and function. 

Spinal Nerves. 

WITH a thorough knowledge of the general properties of 
the nerves belonging to the cerebro-spinal system, the func- 
tions of most of the special nerves are apparent simply from 
their anatomical relations. This is especially true of the 
spinal nerves; which, in general terms, are distributed to 
the muscles of the trunk and extremities, the sphincters, 
and' to the integument covering these parts, the posterior 
segment of the head, and a portion of the mucous mem- 
branes. It is evident, therefore, that an account of the 
exact function of each nervous branch would necessitate a 
full description, not only of the nerves, but of the muscles 
of the body, which is manifestly within the scope only of 
elaborate treatises on descriptive anatomy. It is sufficient 
to indicate, in this connection, that there are thirty-one pairs 
of spinal nerves \ eight cervical, twelve dorsal, five lumbar, 
five sacral, and one coccygeal. Each nerve arises from the 
spinal cord by an anterior (motor) and a posterior (sensory) 



SPINAL NERVES. 123 

root ; the posterior roots being the larger, and having a gan- 
glion. Immediately beyond the ganglion, the two roots 
unite into a single mixed nerve, which passes out of the 
spinal canal by the intervertebral foramen. The nerve thus 
constituted is endowed with both motor and sensory prop- 
erties. It divides outside of the spinal canal into two 
branches, anterior and posterior, both containing motor and 
sensory filaments, which are distributed respectively to the 
anterior and posterior parts of the body. The anterior 
branches are the larger, and supply the limbs and all parts 
in front of the spinal column. 

The anterior branches of the four upper cervical nerves 
form the cervical plexus, and the four inferior cervical nerves, 
with the first dorsal, form the brachial plexus. The anterior 
branches of the dorsal nerves, with the exception of the first, 
supply the walls of the chest and abdomen. These nerves 
go directly to their distribution, and do not first form a 
plexus, like most of the other spinal nerves. The anterior 
branches of the four upper lumbar nerves form the lumbar 
plexus. The anterior branch of the fifth lumbar nerve and 
a branch from the fourth unite with the anterior branch of 
the first sacral, forming the lumbo-sacral nerve, and enter 
into the sacral plexus. The three upper anterior sacral 
nerves with a branch from the fourth form the sacral plexus. 
The greatest portion of the fourth anterior sacral is distrib- 
uted to the pelvic viscera and the muscles of the anus. The 
fifth anterior sacral and the coccygeal are distributed about 
the coccyx. 

The posterior branches of the spinal nerves are very sim- 
ple in their distribution. With one or two exceptions, which 
have no great physiological importance, these nerves pass 
backward from the main trunk, divide into two branches, 
external and internal, and their filaments of distribution go 
to the muscles and integument behind the spinal column. 

It is further important to note, as we shall have occasion 
to do more particularly in connection with the great sym- 



124 NERVOUS SYSTEM. 

pathetic nerve, that all of the cerebro-spinal nerves anas- 
tomose with the sympathetic. This anatomical connection 
between the two systems of nerves has great physiological 
interest. 

Cranial Nerves. 

The nerves which pass out from the cranial cavity present 
certain differences in their arrangement and general proper- 
ties from the ordinary spinal nerves. As we have seen, the 
spinal nerves are exceedingly simple, each one being formed 
by the union of a motor and a sensory root. The function of 
most of them follows as a matter of course when we under- 
stand their general properties and anatomical distribution. 
Many of the cranial nerves, however, are peculiar, either as 
regards their general properties or in their distribution to 
parts concerned in special functions. In some of these 
nerves, the most important facts concerning their distribu- 
tion have only been ascertained by physiological experimen- 
tation, and their anatomy is inseparably connected with 
their physiology. It would be desirable, if it were possible, 
to classify these nerves with reference strictly to their prop- 
erties and functions ; but this can be done only to a certain 
extent, and we must adopt as a basis those divisions recog- 
nized in the best works on anatomy. 

The two classifications of the cranial nerves adopted by 
most anatomists are the arrangement of Willis 1 and of Som- 
mering. 3 The first of these is the more common, and in it 
the nerves are numbered from before backward in the order 
in which they pass out of the skull, making nine pairs. 3 

1 WILLIS, Cerebri Anatome : cut accessit Nervorum Descriptio et Usm, Lon- 
dini, 1664, p. 145, et seq. 

2 SOMMERING, De Basi Encephali et Originibus Nervorum, Goettingae, 1778, 
p. 69, et seq. 

3 Haller adopted the classification of Willis, and his example has been fol- 
lowed by nearly all of the later anatomical and physiological writers, but he dis- 
cards the tenth pair, the suboccipital, or first cervical nerve, originally reckoned 
by Willis with the cranial nerves (HALLER, Elementa Physiologice, Lausannae, 
1762, tomus iv., p. 240.) 



CRANIAL NERVES. 125 

Anatomical Classification of the Cranial Nerve*. 

First Pair. Olfactory ; special nerve of smell. 

Second Pair. Optic ; special nerve of sight. 

Third Pair. Motor oculi communis ; motor nerve die 
tributed to all of the muscles of the eyeball, except the ex- 
ternal rectus and the superior^ oblique, to the iris, and the 
levator palpebrae. 

Fourth Pair. Patheticus, or trochlearis ; a motor 'nerve 
sent to the superior oblique muscle of the eye. 

Fifth Pair. A small motor root (nerve of mastication) 
distributed to the muscles of mastication, and a large root 
(the trifacial), the nerve of general sensibility of the face. 

Sixth Pair. Motor oculi externus, or abducens ; a mo- 
tor nerve passing to the external rectus muscle of the eye. 

Seventh Pair. Portio mollis, or auditory, a special nerve 
of hearing ; and the portio dura, or facial ; a motor nerve 
distributed to the superficial muscles of the face. 

Eighth Pair. Glosso-pharyngeal ; pneumogastric, or par 
vagum ; spinal accessory. Three mixed nerves, with quite 
extensive distributions. 

Ninth Pair. Sublingual, or hypoglossal ; a motor nerve 
distributed to the tongue. 1 

Physiological Classification. 

(a.) Nertes of Special Sense. 
Olfactory. 

Optic. 

Auditory. 

Gustatory, comprising a part of the glosso-pharyngeal 
and a small filament from the facial to the lingual branch of 
the fifth. 

1 According to the classification of Sommering, the arrangement is the same 
for the first, second, third, fourth, fifth, and sixth. The facial is called the sev- 
enth ; the auditory, the eighth ; the glosso-pharyngeal, the ninth ; the pneumo- 
gastric, the tenth; the spinal accessory, the eleventh; and the sublingual, the 
twelfth. 



126 NERVOUS SYSTEM. 

(b.) Nerves of Motion. 

Nerves of motion of the eyeball; comprising the motor 
oculi communis, the patheticus, and the motor oculi externus. 
Nerve of mastication, or motor root of the fifth. 
Facial, sometimes called the nerve of expression. 
Spinal accessory. 
Sublingnal. 

(c.) Nerves of General Sensibility. 

Trifacial, or large root of the fifth. 
A portion of the glosso-pharyngeal. 
Pneumogastric. 

In the above arrangement, the nerves are classified ac- 
cording to their properties at their roots. In their course, 
some of these nerves become mixed, and their branches are 
both motor and sensory, such as the pneumogastric and the 
inferior maxillary branch of the trifacial. 

The nerves of special sense are but slightly, if at all, en- 
dowed with general sensibility ; and, with the exception of 
the gustatory nerves, do not present a ganglion on their 
roots, in this, also, differing from the ordinary sensory 
nerves. They are capable, therefore, of conveying to the 
nerve-centres only certain peculiar impressions, such as 
odors, for the olfactory nerves ; light, for the optic nerves ; 
sound, for the auditory nerves. The proper transmission of. 
these impressions, however, involves the action of accessory 
organs, more or less complex ; and we will pass over the 
properties of these nerves until we come to treat in full of 
the special senses. 

Motor Oculi Communis (Third Nerve). 

The third cranial nerve is the most important of the 
motor nerves distributed to the muscles of the eyeball. Its 
physiology is readily understood in connection with its dis- 
tribution, the only point at all obscure being its relations to 



MOTOR OCULI COMMUNIS. 127 

the movements of the iris, upon which the results of experi- 
ments are somewhat contradictory. As a preface to the 
study of the functions of this nerve, it is necessary to de- 
scribe its anatomical relations. 

Physiological Anatomy. Like all of the cranial nerves, 
this has an apparent origin, where it separates from the en- 
cephalon, and a deep origin, which is the last point to which 
its fibres can be traced in the substance of the brain ; but 
the origin has not the physiological importance attached to 
its ultimate distribution. 

The apparent origin of the nerve is from the inner edge 
of the cms .cerebri, directly in front of the pons Yarolii, 
midway between the pons and the corpora albicantia. It 
presents here from eight to ten filaments, of nearly equal 
size, which soon unite into a single, rounded trunk. 

The deep origin of the nerve has been studied by dissec- 
tions of the encephalon fresh and hardened by different 
liquids. Yulpian, who has made a great number of very 
careful dissections of these nerves, has been able to follow 
the fibres from their apparent origin into the brain-substance 
as tar as the median line.* From the groove by which, they 
emerge from the encephalon, the fibres spread out in a fan- 
shape, the middle filaments passing inward, the anterior, in- 
ward and forward, and the posterior, inward and backward. 
As the result of his observations, Yulpian concludes that 
the middle filaments pass to the median line, and decussate 
with corresponding fibres from the opposite side. The ante- 
rior filaments pass forward and are lost in the optic thala- 
mus. The posterior filaments pass backward, and decussate 
beneath the aqueduct of Sylvius. This apparent decussation 
of the fibres of origin of the third nerves is important in 
connection with the harmony of action of the muscles of 
the eyes and the iris upon the two sides. 

1 VULPIAN, Exsai sur Vorigine de plusieurs paires des nerfs craniens, These, 
Paris, 1853, p. 10, et seq. 
109 



128 NERVOUS SYSTEM. 

The distribution of the third nerve is very simple. As 
it passes into .the orbit by the sphenoidal fissure, it divides 
into two branches. The superior, which is the smaller, 
passes to the superior rectus muscle of the eye, and certain 
of its filaments are continued to the leva tor palpebrse supe- 
rioris. The inferior division breaks up into three branches. 
The internal branch passes to the internal rectus muscle ; 
the inferior branch, to the inferior rectus ; the external 
branch, the largest of the three, is distributed to the inferior 
oblique muscle, and, in its course, sends a short and thick 
filament to the lenticular, or ophthalmic ganglion of the 
.sympathetic. It is this branch which is supposed, through 
the short ciliary nerves passing from the lenticular ganglion, 
to furnish the mofor influence to the iris. 

In its course, this nerve receives a few very delicate fila- 
ments from the cavernous plexus of the sympathetic and a 
branch also from the ophthalmic division of the trifacial. 

Properties and Functions of the Motor Oculi Communis. 
Irritation applied to the root of the third nerve in a living 
animal produces contraction of the f muscles to which it is dis- 
tributed, but no pain. If the irritation, however, be applied 
a little farther on, in the course of the nerve, there are evi- 
dences of sensibility, which is readily explained by its com- 
munications with the ophthalmic branch of the trifacial. At 
its root, therefore, this nerve is exclusively motor, and its 
functions are connected entirely with the actic-n of muscles. 
These facts have been experimentally demonstrated by Lon- 
get * and by Chauveau. 2 

Most of the important facts bearing upon the functions 
of the motor oculi are clearly demonstrable by dividing the 
nerve in a living animal, and are illustrated by cases of its 

1 LONGET, Traite de pliysiologie, Paris, 1869, tome iii., p. 554. 

8 CHAUVEAU, lieckerches physiologiques sur Vorig'me apparente et sur Vorigine 
rfalle des nerfs moteurs craniens. Journal de la physiologic, Paris, 1862, tome 
*., p. 274. 



MOTOR OCULI OOMMTJNIS. 129 

paralysis in the human subject. Heroert Mayo was one of 
the first to experiment upon this nerve in animals living or 
just killed, but his observations were made chiefly with ref- 
erence to the movements of the iris. 1 Bernard, 3 Longet, 8 
and all others who have divided the nerve in living animals, 
are agreed with regard to the phenomena following its sec- 
tion, which depend upon paralysis of the voluntary muscles. 
These phenomena are as follows : 

1. Falling of the upper eyelid, or blepharoptosis. 

2. External strabismus, immobility of the eye, except 
outward, inability to rotate the eye on its antero-posterior 
axis in certain directions, with slight protrusion of the eye- 
ball. 

3. Dilatation of the pupil, with a certain amount of in- 
terference with the movements of the iris. 

The falling of the upper eyelid is constantly observed 
after division of the nerve in living animals, and always fol- 
lows its complete paralysis in the human subject. An ani- 
mal in which the nerve has been divided cannot raise the lid, 
but can approximate the lids more closely, by a voluntary 
effort. In the human subject, the falling of the lid gives to 
the face a very peculiar and characteristic expression. The 
complete loss of power shows that the levator palpebrse su- 
perioris muscle depends upon the third nerve entirely for its 
motor filaments. In pathology, external strabismus is very 
frequently observed without falling of the lid, the filament 
distributed to the levator muscle not being affected. 

1 MAYO, Anatomical and Physiological Commentaries, Number ii., London, 
1823, p. 6 ; and, Outlines of Human Physiology, London, 1827, p. 294. 

2 BERNARD, Lecons sur la physiologic et la pathologic du systeme nerveux, Paris, 
1858, tome ii., p. 204, et seq. 

Bernard gives the following directions for division of the third nerve in the 
rabbit : A small steel hook is introduced along the external wall of the orbit 
into the middle temporal fossa. With the hook the nerve is caught at the ante- 
rior extremity of the fold of the dura mater, which is attached to the sella tur- 
cica, and torn across. In this operation, there are generally evidences of pain 
from the ophthalmic branch of the fifth as it is touched by the instrument 

* Loc.ciL 



130 NEKVOU3 SYSTEM. 

The external strabismus and the immobility of the eye- 
ball except in an outward direction are due to paralysis of 
the internal, superior, and inferior recti muscles, the external 
rectus acting without its antagonist ; a condition which re- 
quires no further explanation. These points are well illus- 
trated by the experiment of dividing the nerve in rabbits. 
If the head of the animal be turned inward, exposing the 
eye to a bright light, the globe will turn outward, by the 
action of the external rectus ; but if the head be turned out- 
ward, the globe remains motionless. 1 

It is somewhat difficult to note the effects of paralysis of 
the inferior oblique muscle, which is also supplied by the 
third nerve. This muscle, acting from its origin at the infe- 
rior and internal part of the circumference of the base of 
the orbit to its attachment at the inferior and external part 
of the posterior hemisphere of the eyeball, gives- to the 
globe a movement of rotation on an oblique, horizontal axis, 
downward and backward, directing the pupil upward and 
outward. When this muscle is paralyzed, the superior 
oblique, having no antagonist, rotates the globe upward and 
inward, directing the pupil downward and outward. The 
action of the oblique muscles is observed when we move the 
head alternately toward one shoulder and the other. In the 
human subject, when the inferior oblique muscle on one side 
is paralyzed, the eye cannot move in a direction opposite to 
the movements of the head, as it does upon the sound side, 
so as to keep the pupil fixed, and the patient has double 
vision. 2 

When all the muscles of the eyeball, except the external 
rectus and superior oblique, are paralyzed, as they are by sec- 
tion of the third nerve, the globe is slightly protruded, simply 
by the relaxation of most of its muscles. An opposite action 
is easily observed in a cat with the facial nerve divided, so 
that it cannot close the lids. When the cornea is touched, 

1 BERNARD, loc. cit. 

2 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 556. 



MOTOR OCTJLI COMitUfflS. 131 

all of the muscles, particularly the four recti, act to draw 
the globe into the orbit, which allows the lid to fall slight- 
ly, and projects the little membrane which serves as a third 
eyelid in these animals. 

Observations with regard to the influence of the third 
nerve upon the movements of the iris have not been so sat- 
isfactory in their results as those relating to the muscles of 
the eyeball. It will be remembered that this nerve sends a 
filament to the ophthalmic ganglion of the sympathetic, and 
that from this ganglion, the short ciliary nerves take their 
origin and pass to the iris. The ganglia of the sympathetic 
system receive branches both from motor and sensory nerves 
belonging to the cerebro-spinal system, and the ophthalmic 
ganglion is no exception to this rule. While it is undoubt- 
edly true that division of the third nerve affects the move- 
ments of the iris, it becomes a question whether this be a 
direct influence, or an influence exerted primarily upon the 
ganglion, not, perhaps, differing from the general effects 
upon the sympathetic ganglia that follow destruction of 
their branches of communication with the motor nerves. 
As yet we know little of the reciprocal influences of the 
cerebro-spinal and the sympathetic system; but some of 
the researches of Bernard into the influence of the sym- 
pathetic ganglia upon the salivary secretion show that the 
submaxillary ganglion, at least, becomes paralyzed, -or loses 
its influence over the secretion of the submaxillary gland, 
after it has been separated for a certain time from the cere- 
bro-spinal system. 1 These considerations, however, belong 
more properly to the sympathetic system. 

The most important experimental observations with re- 
gard to the influence of the third nerve on the iris are the fol- 
lowing : Herbert Mayo made experiments on thirty pigeons, 
living or just killed, upon the action of the optic, the third, 
and the fifth nerves on the iris. He states that when the 

1 BERNARD, Recherches experimentales sur les nerfs vasculaires et calorifiques. 
Journal de la physiologic,, Paris, 1862, tome v., p. 409. 



132 NERVOUS SYSTEM. 

third nerves are divided in the cranial cavity in a living 
pigeon, the pupils become fully dilated, and do not contract 
on the admission of intense light; and, when the same 
nerves are pinched in the living or dead bird, the pupils are 
contracted for an instant on each injury of the nerves. The 
same results follow division or irritation of the optic nerves 
under similar conditions ; but when the third nerves have 
been divided, no change in the pupil ensues on irritating 
the entire or divided optic nerves. 1 

The above experiments are accepted by nearly all physio- 
logical writers ; and the assumption is that the third nerves 
animate the muscular fibres that contract the pupil, the con- 
traction produced by irritation of the optic nerves being re- 
flex in its character. Later observers, however, have carried 
their experiments somewhat further. Longet divided the 
motor oculi and the optic nerve upon the right side. He 
found that irritation of the central end of the divided op- 
tic nerve produced no movement of the pupil of the side 
upon which the motor oculi had been divided, but caused 
contraction of the iris upon the other side. This, taken in 
connection with the fact that, in amaurosis affecting one eye, 
the iris on the affected side will not contract under the stim- 
ulus of light applied to the same eye, but will act when the 
uninjured eye is exposed to the light, further illustrates the 
reflex action which takes place through these nerves. 3 

The reflex action by which the iris is contracted is not 
instantaneous, like most of the analogous phenomena ob- 
served in the cerebro-spinal system, and its operations are 
rather characteristic of the sympathetic system and the non- 
striated muscular tissue. It has been found, also, by Ber- 
nard, in experiments upon rabbits, that the pupil is not 
immediately dilated after division of the third nerve. The 
method employed by Bernard, introducing a hook into the 

1 MAYO, Anatomical and Physiological Commentaries, Number ii., London! 
1823, p. 4. 

8 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 656. 



MOTOE OCULI COMMTJXIS. 133 

middle temporal fossa through the orbit and tearing the 
nerve, can hardly be accomplished without touching the 
ophthalmic branch of the fifth, which produces intense pain, 
and is always followed by a more or less persistent contrac- 
tion of the pupil. Several hours after the operation, how- 
ever, the pupil is generally found dilated, and may slowly 
contract when the eye is exposed to the light. In one ex- 
periment, this occurred after the eye had been exposed for 
an hour. But further experiments by Bernard show that 
although the pupil contracts feebly and slowly under the 
stimulus of light after division of the motor oculi, it will di- 
late under the influence of belladonna, and can be made to 
contract by operating upon other nerves. It is well known, 
for example, that division or irritation of the fifth nerve 
produces contraction of the pupil. This takes place after 
division of the third nerve as well as before. Section of the 
sympathetic in the cervical region also contracts the pupil, 
and this occurs after paralysis of the motor oculi. 1 These 
facts show that the third nerve is not the only one capable 
of acting upon the iris, and that it is not the sole avenue for 
the transmission of reflex influences. 

Bernard also found that galvanization of the motor oculi 
itself did not produce contraction of the pupil, but this re- 
sult followed when he galvanized the ciliary nerves coming 
from the ophthalmic ganglion. 2 Chauveau states, that in 
experiments upon horses, he has not observed contraction of 
the pupil following galvanization of the motor oculi, though 
he has sometimes seen it in rabbits. 3 At all events, contrac- 
tion is by no means constant ; and when it occurs, it prob- 
ably depends upon stimulation of the ciliary nerves them- 
selves or irritation of the ophthalmic branch of the fifth, and 
not upon stimulation of the trunks of the third pair. 

1 BERNARD, Systeme nerveux, Paris, 1858, tome ii., p. 201, et seq. 

8 Op at., p. 211. 

3 CHAUVEAU, Recherches pkysiologiques sur Torigine apparante et sur Forigine 
reelle des nerfs moteurs craniens. Journal de la physiologic, Paris, 1862, tome 
v, p. 274. 



134 NERVOUS SYSTEM. 

The movements of the iris will be treated of again, in 
connection with the physiology of vision ; but we may here 
allude to an interesting fact observed by Miiller, which re- 
lates to the action of the motores oculorum. When the eye 
is turned inward by a voluntary effort, the pupil is always 
contracted ; and when the axes of the two eyes are made to 
converge strongly, as in looking at near objects, the contrac- 
tion is very great. 1 

The following case, kindly sent for examination by Dr. 
Althof, of the New York Eye Infirmary, illustrates, in the 
human subject, nearly all of the phenomena following pa- 
ralysis of the motor oculi communis in experiments upon 
the lower animals : 

The patient was a girl, nineteen years of age, with com- 
plete paralysis of the nerve upon the left side. There was 
slight protrusion of the eyeball, complete ptosis, with the 
pupil moderately dilated and insensible to ordinary im 
pressions of light. The sight was not affected, but there 
was double vision, except when objects were placed before 
the eyes so that the axes were parallel, or when an object 
was seen with but one eye. The axis of the left eye was 
turned outward, but it was not possible to detect any devia 
tion upward or downward. Upon causing the patient to 
incline the head alternately to one shoulder and the other, 
it was evident that the affected eye did not rotate in the 
orbit but moved with the head. This seemed to be a case 
of complete and uncomplicated paralysis of the third nerve 

Patketicus, vr Trochlearis (Fourth Nerve). 

Except as regards the influence of the motor oculi coin- 
munis upon the iris, the patheticus is to be classed with the 
other motor nerves of the eyeball. Its physiology is ex- 
tremely simple, and resolves itself into the action of a single 
muscle, the superior oblique. It will be necessary, there- 
fore, only to describe its origin, distribution, and connections. 

1 MULLER, Elements of Physiology ', London, 1840, vol. L, p. 827. 



PATHETICUS. 135 

Physiological Anatomy. The apparent origin of the 
patheticus is from the superior peduncles of the cerebellum ; 
but it may be easily traced to the valve of Yieussens. Ac- 
cording to Yulpian, the deep roots, which are covered by 
an extremely thin layer of nerve-substance, can be traced, 
passing from without inward, to the following parts : One 
filament is lost in the substance of the peduncles; other 
filaments pass from before backward into the valve' of Yi- 
eussens and are lost, and a few pass into the frenulum ; a 
few filaments pass backward and are lost in the corpora 
quadrigemina ; but the greatest number pass to the median 
line and decussate with corresponding filaments from the 
opposite side. Yulpian states that this decussation is quite 
as distinct as that of the anterior pyramids of the medulla 
oblongata, and that he has been able to follow fibres across 
the median line on either side. 1 The decussation of the 
fibres of origin of the fourth nerves has the same physio- 
logical significance as the decussation of the roots of the 
third. 

From this origin, the patheticus passes into the orbit by 
the sphcnoidal fissure, and is distributed to the superior 
oblique muscle of the eyeball. In the cavernous sinus, it 
receives branches of communication from the ophthalmic 
branch of the fifth, but these are not closely united with the 
nerve. A small branch passes into the tentorium, and one 
joins the lachrymal nerve, these, however, being exclusively 
sensitive and coming from the ophthalmic branch of the 
fifth. 2 It also receives a few filaments from the sympathetic. 

Properties and Functions of the Patheticus. Direct ob- 
servations upon the patheticus in living animals have shown 
that it is motor, and its galvanization excites contraction of 
the superior oblique muscle only. These facts have been 

1 VULPIAX, Essai sur Torigine de plusieurs paires des nerfs craniens, 
Paris, 1853, p. 15. 

2 SAPPEY, Traite d'ancdomie descriptive, Paris, 1852, tome ii., p. 209. 



136 NEKVOTJS SYSTEM. 

ascertained by Longet 1 and by Chauveau. 3 The question 
of the function of the nerve, therefore, resolves itself sim- 
ply into the mode of action of the superior oblique muscle. 
This muscle arises just above the inner margin of the optic 
foramen, passes forward, along the upper wall of the orbit 
at its inner angle, to a little cartilaginous ring which serves 
as a pulley. From its origin to this point it is muscular. 
Its tendon becomes rounded just before it passes through 
the pulley, where it makes a sharp curve, passes outward 
and slightly backward, and becomes spread out to be at- 
tached to the globe at the superior and external part of its 
posterior hemisphere. It acts upon the eyeball from the 
pulley at the upper and inner portion of the orbit as the 
fixed point, and rotates the eye upon an oblique, horizontal 
axis, from below upward, from without inward, and from 
behind forward. By its action, the pupil is directed down- 
ward and outward. It is the direct antagonist of the in- 
ferior oblique, the action of which has been described in 
connection with the motor oculi communis. "When the pa- 
theticus is paralyzed, the eyeball is immovable, as far as 
rotation is concerned ; and when the head is moved toward 
the shoulder, the eye does not rotate to maintain the globe 
in the same relative position, and we have double vision. 3 

Motor Oculi Externus, or Abducens (Sixth Nerve). 

Like the patheticus, the motor oculi externus is distrib- 
uted to but a single muscle, the external rectus. Its uses, 
therefore, are apparent from a study of its properties and 
distribution. 

Physiological Anatomy. The apparent origin of the 
sixth nerve is from the groove which separates the anterior 

1 LONGET, Traite de physiologic, Paris, 1869, tome Hi., p. 559. 

8 CHAUVEAU, Recherches physiologiques sur Vorigine apparante el sur VorigvM 
r&elle des nerfs moteurs craniens. Journal de la physiologic, Paris, 1862, tome v., 
p. 275. 

8 See page 130. 



MOTOR OCULI EXTERNTTS. 137 

corpus pyramidale of the medulla oblongata from the pons 
Yarolii, and from the upper portion of the medulla and the 
lower portion of the pons next the groove. Its origin at 
this point is by two roots : an inferior, which is the larger, 
and comes from the corpus pyramidale ; and a superior root, 
sometimes wanting, which seems to come from the lower 
portion of the pons. All anatomists are agreed that the 
deep fibres of origin of this nerve pass to the gray matter 
in the floor of the fourth ventricle. Vulpian has followed 
these fibres to within about two-fifths of an inch of the me- 
dian line, but could not trace them beyond this point. 1 It 
is not known that the fibres on the two sides decussate. 

From this origin, the nerve passes into the orbit by the 
sphenoidal fissure, and is distributed exclusively to the ex- 
ternal rectus muscle of the eyeball. In the cavernous sinus, 
it anastomoses with the sympathetic through the carotid 
plexus and Meckel's ganglion. It also receives sensitive 
filaments from the ophthalmic branch of the fifth. It is 
stated by Longet, a Sappey, 8 and others, that this nerve occa- 
sionally sends a small filament to the ophthalmic ganglion ; 
and it is supposed by Longet that this branch, which is ex- 
ceptional, exists in those cases in which paralysis of the mo- 
tor oculi communis, which usually furnishes all the motor 
filaments to this ganglion, is not attended with immobility 
of the iris. 

Properties and Functions of the Motor Oculi Externus. 
Direct experiments, the most satisfactory being those of 
Longet 4 and of Chauveau, 6 have shown that the motor oculi 
communis is entirely insensible at its origin, its stimulation 
producing contraction of the external rectus muscle and no 

1 YULPIAN, Essai sur Vorigine de plusieurs paires des nerfs rachidiens, These, 
Paris, 1853, p. 29. 

8 LOXGET, Traite de physiologic, Paris, 1869, tome in., p. 561. 

3 SAPPET, Traite cTanatomie descriptive, Paris, 1852, tome ii., p. 249. 

4 LOXGET, op. tit., tome iii., p. 560. 

6 CHAUVEAU, op. cit. Journal de la physiologic, Paris, 1862, tome v., p. 275. 



138 NERVOUS SYSTEM. 

pain. The same experiments illustrate the function of the 
nerve, inasmuch as its irritation is followed by powerful con- 
traction of the muscle and deviation of the eye outward. 
Division of the nerve in the lower animals or its paralysis 
in the human subject is attended with internal, or converg- 
ing strabismus, from the unopposed action of the internal 
rectus muscle. 

"With regard to the associated movements of the eyeball, 
it is a curious ftict that all of the muscles of the eye that 
have a tendency to direct the pupil inward or to produce 
the simple movements upward and downward ; viz., the in- 
ternal, inferior, and superior recti, are animated by a single 
nerve, the motor oculi communis, this nerve also supplying 
the inferior oblique ; and that each muscle that has a ten- 
dency to move the globe so as to direct the pupil outward, 
except the inferior oblique ; viz., the superior oblique and 
the external rectus, is supplied by a special nerve. The 
various movements of the eyeball will be studied more 
minutely in connection with the physiology of vision. 



CHAPTER Y. 

MOTOR NERVES OF THE FACE. 

Nerve of mastication (the small, or motor root of the fifth) Physiological anat- 
omy Deep origin Distribution Properties and functions of the nerve 
of mastication Facial nerve, or nerve of expression (the portio dura of the 
seventh) Physiological anatomy Intermediary nerve of "Wrisberg De- 
cussation of the fibres of origin of the facial Alternate paralysis Course 
and distribution of the facial Anastomoses with sensitive nerves Summary 
of the anastomoses and distribution of the facial Properties and functions 
of the facial Functions of the branches of the facial within the aqueduct 
of Fallopius Functions of the chorda tympani Influence of various 
branches of the facial upon the movements of the palate and uvula Func- 
tions of the external branches of the facial 

THE motor nerves of the face are, the small, or motor 
root of the fifth, and the portio dura of the seventh, or the 
facial. The first of these nerves is distributed to the deep 
muscles, those concerned in the act of mastication, and the 
second, the facial, supplies the superficial muscles of the face, 
and is sometimes called the nerve of expression. These 
nerves are not so simple in their anatomy and physiology as 
the motor nerves of the eyeball. The nerve of mastication, 
at its origin, is deeply situated at the base of the brain, and 
is exposed and operated upon with difficulty. It passes out 
of the cranium, closely united with one of the great sensitive 
branches of the fifth, and its distribution has been most suc- 
cessfully studied by experiments in which it is divided in the 
cranial cavity. The origin of the facial is also reached with 
great difficulty. It communicates with other nerves, and 
its physiology has been most satisfactorily studied by di- 



140 NEKVOUS SYSTEM. 

viding it at its origin or in different portions of its course. 
In treating of these nerves, we shall first, as in the case of 
the motor nerves of the eye, study their properties at their 
roots, noting the phenomena following their galvanization 
and section. It will be necessary, also, to describe their ori- 
gin and distribution, as far as has been ascertained by dissec- 
tion. 

Nerve of Mastication (the Small, or Motor Root of the 

Fifth). 

The motor root of the fifth nerve is entirely distinct from 
its sensitive portion, until it emerges from the cranial cavity 
by the foramen ovale. It is then closely united with the 
inferior maxillary branch of the large root ; but at its origin 
it has been shown to be motor, and its section in the cranial 
cavity has demonstrated its distribution to a particular set 
of muscles. 

Physiological Anatomy. The apparent origin of the 
fifth nerve is from the lateral portion of the pons Varolii. 
The small, or motor root arises from a point a little higher 
and nearer the median line than the large root, from which 
it is separated by a few fibres of the white substance of the 
pons. The most satisfactory investigations with regard to 
the deep origin of the small root are those of Yulpian. Ac- 
cording to this observer, the dissections should be made after 
the specimen has been kept in alcohol for about fifteen days, 
and before the parts are thoroughly hardened. At the point 
of apparent origin, the small root presents "from six to eight 
rounded filaments. If a thin layer of the pons covering 
these filaments be removed, the roots will be found pene- 
trating its substance, becoming flattened, passing under the 
superior peduncles of the cerebellum, and going to the ante- 
rior wall of the fourth ventricle. At this* point, they change 
their direction, passing now from without inward, and from 
behind forward toward the median line, the fibres diverging 



NERVE OF MASTICATION. 141 

rapidly. The posterior fibres pass to the median line, and 
Yulpian has seen certain of these decussate with fibres from 
the opposite side. The anterior fibres pass toward the aque- 
duct of Sylvius and are lost. The fibres become changed in 
their character when they are followed inward beyond the 
anterior wall of the fourth ventricle. Here they lose their 
white color, become gray, and present numerous globules of 
gray substance between their filaments. 1 

From the origin above described, the small root passes , 
beneath the ganglion of Gasser, from w^hich it sometimes, 
though not constantly, receives a filament of communication, 
lies behind the inferior maxillary branch of the large root, 
and passes out of the cranial cavity by the foramen ovale. 
Within the cranium, the two roots are distinct ; but after the 
small root passes through the foramen, it is united by a mu- 
tual interlacement of fibres with the sensitive branch. 9 

The course of the motor root of the fifth possesses little 
physiological interest. It is sufficient in this connection to 
note that the inferior maxillary nerve, made up of the motor 
root and the inferior maxillary branch of the sensitive root, 
just after it passes out by the foramen ovale, divides into 
two .branches, anterior and posterior. The anterior branch, 
which is the smaller, is composed almost entirely of motor 
filaments, and is distributed to the muscles of mastication. 
It gives off five branches. The first of these passes to be 
distributed to the masseter muscle, in its course occasionally 
giving off a small branch to the temporal muscle and a fila- 
ment to the articulation of the inferior maxillary with the 
temporal bone. The two deep temporal branches are dis- 
tributed to the temporal muscle. The buccal branch sends 
filaments to the external pterygoid and to the temporal 
muscle, and a small branch is distributed to the inter- 
nal pterygoid muscle. From the posterior branch, which 

1 YULPIAN, Essai sur Torigine de plusieurs paires des nerfs craniens, Thfee, 
Paris, 1853, p. 21. 

2 SAPPEY, Traite cTanatomie descriptive, Paris, 1852, tome ii., p. 233. 



142 NERVOUS SYSTEM. 

is chiefly sensitive, but contains some motor filaments, 
branches are sent to the mylo-hyoid muscle, and to the an- 
terior belly of the digastric. In addition, the motor branch 
of the fifth sends filaments to the tensor muscles of the ve- 
lum palati. 

The above description shows, in general terms, the dis- 
tribution of the nerve of mastication, without taking into 
consideration its various anastomoses, the most important 
of which are with the facial. Physiological experiments 
have shown that the buccinator muscle receives no motor 
filaments from the fifth, but is supplied entirely by the facial. 
Mayo found that pinching the branch of the fifth which 
penetrates the buccinator muscle produced no action upon 
it. 1 Longet has galvanized the buccal branch of the fifth 
without producing contraction of this muscle, which always 
contracts upon galvanizing the facial. 2 The buccal branch 
of the fifth sends motor filaments only, to the external ptery- 
goid and the temporal, its final branches of distribution be- 
ing sensitive and going to integument and mucous mem- 
brane. 

In another volume we have given a table of the muscles 
of mastication, with a description of their action. 3 It will 
be seen by this table that the following muscles depress 
the lower jaw ; viz., the anterior belly of- the digastric, 
the mylo-hyoid, the genio-hyoid, and the platysma myoides. 
Of these, the digastric and the mylo-hyoid are animated by 
the motor root of the fifth ; the genio-hyoid is supplied by 
filaments from the sublingual ; and the platysma myoides, by 
branches from the facial and from the cervical plexus. All 
of the muscles which elevate the lower jaw and move it lat- 
erally and antero-posteriorly ; viz., the temporal, masseter, 
and the internal and external pterygoids, the muscles most 

1 MAYO, Anatomical and Physiological Commentaries, Number il, London, 
1823, p. 8. 

8 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 663. 
8 See vol. ii., Digestion, p. 147, et seq. 



NEBVE OF MASTICATION. 143 

actively concerned in mastication, are animated by the mo- 
tor root of the fifth. 

Properties and Functions of the Nerve of Mastimtion. 
The anatomical distribution of the small root of the fifth 
nerve points at once to its function. Charles Bell, whose 
ideas of the nerves were derived almost entirely from their 
anatomy, called it the nerve of mastication, in 1821, though 
he does not state that any experiments were made with re- 
gard to its function. 1 All anatomical and physiological 
writers since that time have adopted this view. It would be 
difficult, if not impossible, to galvanize the root in the cra- 
nial cavity in a living animal ; but its galvanization, prob- 
ably in an animal just killed, has been shown by Longet, 
before 1 842, to determine very marked movements of the 
lower jaw. 2 Longet states in his work on physiology that 
no contractions of the muscles of mastication are produced 
when the large root of the fifth alone is galvanized. The 
experiments demonstrating this fact were made on horses 
and dogs, operating upon the roots of the nerves after re- 
moving the cerebral lobes. 3 Chauveau also found that gal- 
vanization of the small root of the fifth produced contrac- 
tion of the muscles which elevate the lower jaw sufficiently 
sudden and violent to break sometimes, in old horses, little 
fragments from the irregular surfaces of the teeth.* 

The above experiments are sufficient to show the physio- 
logical properties of the small root, which is without doubt 
solely a nerve of motion. 

1 BELL, On the Nerves; giving an Account of some Experiments on their 
Structure and Functions, which lead to a New Arrangement of the System. 
Philosophical Transaction^ London, 1821, Part i., p. 417. 

8 LONGET, Anatomic et physiologic du systeme ncrveux, Paris, 1842, tome iL, 
p. 190. 

3 LOXGET, Traite de physiologic, Paris, 1869, tome iii., p. 562. 

4 CHAUVEAU, Recherches physiologiques sur Vorigine apparante et sur Foriffine 
r'edle des nerfs moteurs craniens. Journal de la physiologic, Paris, 1862, tome 
v., p. 276. 

110 



144: NEKVOTJS SYSTEM. 

The observations upon the division of the fifth pair in 
the cranial cavity, made by Fodera, Mayo, Magendie, Ber- 
nard, and others, are most interesting in connection with the 
functions of its sensitive branches, and will be referred to in 
detail in treating of the properties of the large root. In ad- 
dition to the loss of sensibility following section of the entire 
nerve, Bernard has noted carefully the effects of division of 
the small root, which cannot be avoided in the operation. 
In rabbits, the paralysis of the muscles of mastication upon 
one side, and the consequent action of the muscles upon the 
unaffected side only, produce, a few days after the opera- 
tion, a remarkable change in the appearance of the incisor 
teeth. As the teeth in these animals are gradually worn 
away in mastication and reproduced, the lower jaw being 
deviated by the action of the muscles of the sound side, the 
upper incisor of one side and the lower incisor of the other 
touch each other but slightly and the teeth are worn uneven- 
ly. This makes the line of contact between the four incisors, 
when the jaws are closed, oblique instead of horizontal. 1 "We 
have often divided the fifth pair in the cranial cavity in rab- 
bits, by the method employed by Magendie and Bernard, 
and have repeatedly verified these observations. 

There is little left to say with regard to the functions of 
the motor root of the fifth nerve, in addition to our descrip- 
tion of the action of the muscles of mastication, contained in 
the volume on digestion, 8 except as regards the action of the 
filaments sent to the muscles of the velum palati. In deg- 
lutition, the muscles of mastication are indirectly involved. 
This act cannot be well performed unless the mouth be 
closed by these muscles. When the food is brought in con- 
tact with the velum palati, muscles are brought into action 
which render this membrane tense, so that the opening is 
adapted to the size of the alimentary bolus. These muscles 

1 BERNARD, Lemons sur la physiologic et la pathologic du systeme 
Paris, 1858, tome ii., p. 100. 

4 See vol. ii., Digestion, p. 147, et seq. 



FACIAL NERVE. 145 

are animated by the motor root of the fifth. This nerve, 
then, is not only the nerve of mastication, animating all of 
the -muscles concerned in this act, except two of the most 
unimportant depressors of the lower jaw (the genio-hyoid 
and the platysma myoides), but it is concerned indirectly in 
deglutition. 

Facial Nerve, or Nerve of Expression (the Portio dura of 
the Seventh). 

The facial, the portio dura of the seventh according to 
the arrangement of Willis, is one of the most interesting of 
the cranial nerves. Its anatomical relations are quite intri- 
cate, and its communications with other nerves, very numer- 
ous. As far as can be determined by experiments upon 
living animals, this nerve is exclusively motor at its origin ; 
but in its course it presents anastomoses with the sympa- 
thetic, with branches of the. fifth, and with the cervical 
nerves, undoubtedly receiving sensory filaments. While 
the chief physiological interest attached to this nerve de- 
pends upon its action upon muscles, it is important to study 
its origin, distribution, and communications. 

Physiological Anatomy. The portio dura of the seventh 
has its apparent origin from the lateral portion of the me- 
dulla oblongata, in the groove between the olivary and the 
restiform body, just below the border of the pons Varolii, its 
trunk being internal to the trunk of the portio mollis, or au- 
ditory nerve. It is separated from the auditory by the two 
filaments constituting what is known as the intermediary 
nerve of Wrisberg, or the portio inter duram et mollem. 
As this little nerve joins the facial, it must be included in 
its root. It is called the accessory root by Sappey. 1 

There are certain pathological considerations which ren- 
der the deep, or real origin of the facial a question of the 

1 SAPPEY, Traite d'anatomie descriptive, Paris, 1852, tome ii., p. 251. 



146 NERVOUS SYSTEM. 

greatest interest and importance. In liemiplegia from in- 
jury of the substance of the encephalon, particularly from 
haemorrhage, there is almost always more or less paralysis 
of the superficial muscles of the face. It has been observed 
that in certain cases, the facial paralysis exists upon the 
same side as the hemiplegia, the side opposite to the cere- 
bral lesion, while in others, the palsy of the face is on the 
same side as the lesion, the general hemiplegia being, as 
usual, upon the opposite side. To explain these phenomena 
theoretically, we must assume that in some cases, the brain- 
lesion is to be located at a point where it involves the fila- 
ments of origin of the facial, following them from without 
inward, before they decussate, which would produce facial 
paralysis on the same side as the lesion and none on the side 
affected with general hemiplegia ; while in other cases, the 
injury to the brain involves the roots of the facial after they 
have decussated, when the paralysis of the face would be on 
the same side as the paralysis of the rest of the body. It 
would be interesting to see how far these pathological facts, 
with their theoretical explanation, correspond with anatomi- 
cal researches into the real origin of the nerves. 

Many anatomists have endeavored to trace the fibres of 
the facial from their point of emergence from the encepha- 
lon to their true origin, but with results not entirely satis- 
factory. At the present day, it is pretty generally agreed 
that the fibres pass inward, with one or two deviations from 
a straight course, to the floor of the fourth ventricle, where 
they spread out and become fan-shaped. In the floor of the 
fourth ventricle, certain of the fibres have been thought to 
terminate in the cells of the gray substance, and others have 
been traced to the median line, where they decussate ; the 
course of most of the fibres, however, has never been satis- 
factorily established. 

It is evident, from physiological experiments, that the 
decussation of the fibres in the floor of the fourth ventricle 
itself is not very important. Yulpian has made, in dogs 



FACIAL NERVE. 14:7 

and rabbits, a longitudinal section in the middle line of the 
ventricle, which would necessarily have divided the fibres 
passing from one side to the other, without producing nota- 
ble paralysis of the facial nerves upon either side. 1 This 
single fact is sufficient to show that the main decussation of 
the fibres animating the muscles of the face takes place, if 
at all, at some other point. 

The following curious phenomenon, however, resulting 
from this section, was noted by Yulpian : He found that 
although there was no apparent paralysis of the orbicularis 
muscle of the eye upon either side, the synchronism of the 
movements of the two muscles seemed to be destroyed. It 
is well known that in man, and in many of the lower ani- 
mals, there is an involuntary action of these muscles simul- 
taneously on the two sides in winking. After a longitudinal 
section in the median line of the floor of the fourth ventri- 
cle, the animals winked with either eye alternately, or with 
one eye for a time without closing the other, but there was 
no simultaneous action of the muscles on the two sides. 2 

The pathological facts bearing upon the question of de- 
cussation of the filaments of origin of the facial have long 
been recognized. They are, in brief, as follows : When 
there is a lesion of the brain-substance anterior to the pons 
Yarolii, the phenomena due to paralysis of the facial are 
observed on the same side as the hemiplegia, opposite to the 
side of injury to the brain. "When the lesion is either in the 
pons or below it, the face is affected on the same side, and 
not on the side of the hemiplegia. In view of these facts, 
the remarkable phenomenon of hemiplegia upon one side 
and facial paralysis upon the other is regarded as indi- 
cating, with tolerable certainty, that the injury to the brain 
has occurred upon the same side as the facial paralysis, 
either in or posterior to the pons Yarolii. It is unnecessary 

1 VULPIAK, Lemons sur la phy&iologie generate et comparee du systeme nervevx, 
Paris, 1866, p. 480. 

2 VCLPIAX, op. cit., p. 481. 



148 NERVOUS SYSTEM. 

to enter into a farther discussion of these facts, which are ac- 
cepted by nearly all writers upon diseases of the nervous sys- 
tem, and may be regarded as settled ; 1 and the only question 
is, how far they can be explained by the anatomy of the parts. 

As we have just seen, the fibres of origin of the facial 
have been traced to the floor of the fourth ventricle, where 
a few decussate, but the rest are lost. Ths question now is, 
whether or not the fibres pass up through the pons, and de- 
cussate above, as the pathological facts just noted would 
seem to indicate. Anatomical researches upon this point 
are entirely unsatisfactory ; and the existence of such a de- 
cussation has never been clearly demonstrated. The patho- 
logical observations, nevertheless, remain ; and, however in- 
definite anatomical researches may have been, there can be 
no doubt that lesions in one-half of the pons affect the facial 
upon the same side, while lesions above have a crossed ac- 
tion. The most that we can say upon this point is, that it 
is a reasonable inference from pathological facts that the 
nerves decussate anterior to the pons. 

It will be only necessary to describe in a general way the 
course of the fibres of distribution of the facial. The main 
root of the facial, the auditory nerve, and the delicate inter- 
mediary nerve of Wrisberg pass together into the internal 
auditory rneatus. At the bottom of the meatus, the facial 
and the nerve of Wrisberg enter the aqueeductus Fallopii, 
following its course through the petrous portion of the tem- 
poral bone. In the aqueduct, the nerve of "Wrisberg pre- 
sents a little ganglioform enlargement, of a reddish color, 
which has been shown to contain nerve-cells. 2 The main 

1 The reader is referred for a fuller consideration of these points to the re- 
cent standard works upon practical medicine. The most complete collection of 
cases of the so-called alternate paralysis was published by Gubler, in the Ga- 
zette hebdomadaire de medecine et chirurgie, Paris, 1856, and in the volumes of 
the same journal for 1858 and 1859. A characteristic case has lately been re- 
ported by Prof. Hammond, in the Journal of Psychological Medicine, New York, 
1871, vol. v., p. 14. 

8 SAPPEY, Traite d 1 'anatomic descriptive, Paris, 1862, tome ii., p. 254. 



FACIAL NERVE. 149 

root and the intermediary nerve then unite and form the 
common trunk of the facial, which emerges from the cranial 
cavity by the stylo-mastoid foramen. 

In the aquseductus Fallopii, the facial gives off numerous 
branches, as follows : 

1. The large petrosal branch is given off from the gan- 
glioform enlargement, and goes to MeckePs ganglion. 

2. The small petrosal branch is given off at the ganglio- 
form enlargement, or a very short distance beyond it, and 
passes to the otic ganglion. 

3. A small branch, the tympanic, is distributed to the 
stapedius muscle. 

4. The chorda tympani, a branch of great physiological 
interest, passes through the cavity of the tympanum, and 
joins the lingual branch of the inferior maxillary division 
of the fifth as it passes between the two pterygoid muscles, 
with which nerve it becomes closely united. 

5. Opposite to the point of origin of the chorda tym- 
pani, a communicating branch passes between the facial and 
the pneumogastric, connecting these nerves by a double in- 
osculation. 

The five branches above described are given off in the 
aquseductus Fallopii. 1 The following branches are given off 
after the nerve has emerged from the cranial cavity : 

1. Just after the facial has passed out at the stylo-mastoid 
foramen, it sends a small communicating branch to the 
glosso-pharyngeal nerve. According to Sappey, this branch 
is sometimes wanting. 3 

2. The posterior auricular nerve is given off by the facial 
a little below the stylo-mastoid foramen. Its superior branch 
is distributed to the retrahens aurem and the attollens aurem. 

1 In the course of the facial in the aqueduct, two branches are sometimes 
described, one going to the auditory, and another to the sympathetic filaments 
accompanying the middle meningeal artery ; but their existence is denied by 
many anatomists. 

2 SAPPEY, Traite d'anatomie descriptive, Paris, 1852, tome ii., p. 259. 



150 NERVOUS SYSTEM. 

In its course, this nerve receives a communicating branch 
of considerable size from the cervical plexus, by the auricu- 
laris magnus. It sends some filaments to the integument. 
The inferior, or occipital branch, the larger of the two, is 
distributed to the occipital portion of the occipito-frontalis 
muscle and to the integument. 

3. The digastric branch is given off near the root of the 
posterior auricular. It is distributed to the posterior belly 
of the digastric muscle. In its course, it anastomoses with 
filaments from the glosso-pharyngeal nerve. From the 
plexus formed by this anastomosis, filaments are given off 
to the digastric and to the stylo-hyoid muscle. 

4. Near the stylo-mastoid foramen, a small branch is 
given off, which is distributed exclusively to the stylo-hyoid 
muscle. 

5. Near the stylo-mastoid foramen, or sometimes a little 
above it, a long and exceedingly delicate branch is given off, 
which is not noticed in most works on anatomy. It is de- 
scribed, however, by Hirschfeld, under the name of the lin- 
gual branch. 1 It passes behind the stylo-pharyngeal muscle, 
and then by the sides of the pharynx to the base of the 
tongue. In its course, it receives one or two branches from 
the glosso-pharyngeal nerve, which are nearly as large as the 
original branch from the facial. As it passes to the base of 
the tongue, it anastomoses again by numerous filaments 
with the glosso-pharyngeal. It then sends filaments of dis- 
tribution to the mucous membrane, and finally passes to the 
stylo-glossus and the palato-glossus muscle. 

Having given off these branches, the trunk of the facial 
passes through the parotid gland, dividing into its two great 
terminal branches. 

1. The temporo-facial branch, the larger, passes upward 
and forward to be distributed to the superficial muscles of 
the upper part of the face; viz., the attrahens aurem, the 

1 LUDOVIC HIRSCHFELD, Traite et iconographie du systeme nerveux, Paris, 1866, 
p. 206, and, Atlas, PI. xxx., Figs. 2, 13. 



FACIAL NERVE. 151 

frontal portion of the occipito-frontalis, the orbicnlaiis pal- 
pebrarum, corrugator supercilii, pyraniidalis nasi, levator 
labii superioris, levator labii superioris alseque nasi, the dila- 
tors and compressors of the nose, part of the buccinator, 
the levator anguli oris, and the zygomatic muscles. In its 
course, it receives branches of communication from the au- 
riculo-temporal branch of the inferior maxillary nerve. It 
joins also with the temporal branch of the superior -maxil- 
lary and with branches of the ophthalmic. In its course, it 
thus becomes a mixed nerve, and is distributed in part to 
integument. 

2. The cervico-facial nerve passes downward and forward 
to supply the buccinator, orbicularis oris, risorius, levator 
labii inferioris, depressor labii inferioris, depressor anguli 
oris, and platysma. 

Summary of the Anastomoses and Distribution of the 
Facial. In the aquseductus Fallopii, filaments of communi- 
cation go to Meckel's ganglion and the otic ganglion of the 
sympathetic. The chorda tympani joins the lingual branch 
of the inferior maxillary division of the fifth. A branch is 
also sent to the pneumogastric. After the nerve has passed 
out by the stylo-mastoid foramen, it sends a communicating 
branch to the glosso-pharyngeal, and receives a branch from 
the auricularis magnus. It anastomoses, also, outside of the 
cranium, with the glosso-pharyngeal. In the course of the 
nerve, it receives anastomosing filaments from the three 
great divisions of the fifth. 

It is thus seen that the facial, in its course, receives nu- 
merous filaments from the great sensitive nerve of the face. 
Certain of its fibres of distribution go to integument. 

The muscles supplied by the facial are the stapedius, and 
probably the tensor tympani, of the internal ear, the muscles 
of the external ear, the occipito-frontalis, the posterior belly 
of the digastric, the stylo-hyoid, the stylo-glossus, and the 
palato-glossus. The two great branches of distribution, the 
temporo-facial and the cervico-facial, are distributed to all of 



152 NERVOUS SYSTEM. 

the superficial muscles of the face, leaving the deep muscles, 
or the muscles of mastication, to be supplied by the motor 
root of the fifth. In addition, it supplies in part the platys- 
ma myoides. "VYe have already seen that the buccal branch 
of the small root of the fifth is not distributed to the 
buccinator, but that this muscle is supplied exclusively by 
branches from the facial. 1 

Properties and Function of the Facial Nerve. It has 
long been recognized that the facial is the motor nerve of 
the superficial muscles of the face, and that its division pro- 
duces paralysis of motion and no marked effects upon sensa- 
tion. It is evident, also, from the numerous communica- 
tions of the facial with the fifth, that it probably contains in 
its course sensitive fibres. Indeed, all who have operated 
upon this nerve have found that it is slightly sensitive after 
it has emerged from the cranial cavity. It is a question, 
however, of great importance to determine, whether or not 
the facial be endowed with sensibility by virtue of its own 
fibres of origin. The main root is evidently from the motor 
tract, resembles the anterior roots of the spinal nerves, and 
is distributed to muscles ; but this is joined by the interme- 
diary nerve of "Wrisberg, which presents a small enlarge- 
ment, undoubtedly containing nerve-cells, somewhat analo- 
gous to the ganglia upon the posterior roots of the spinal 
nerves. 

If the facial possess any sensibility at its root, it is but 
slight. In the early experiments of Sir Charles Bell, irrita- 
tion of the facial exposed in an ass apparently produced no 
pain, 2 but the roots were not exposed in the cranial cavity. 
Magendie, on the other hand, in repeating these observa- 
tions, found the nerve distinctly sensitive. 3 Longet, and 

1 See page 142. 

2 BELL, On the Nerves, etc. Philosophical Transactions, London, 1821, Part 
I., pp. 413, 418. 

8 MAGENDIE, Journal de physiologic, Paris, 1822, tome ii., p. 67, note. 



FACIAL NERVE. 153 

most other experimenters, have also demonstrated the sen- 
sibility of the nerve after it has passed out of the cranial 
cavity, 1 except the inferior branch, in which Magendie and 
others have found no evidences of pain on irritating it in 
living animals. 2 Experiments have further shown that the 
facial derives its sensibility in greatest part from the fifth 
pair ; for section of the latter within the cranial cavity has 
been found by Magendie to destroy the sensibility pf the 
seventh. 3 It is probable, however, from other experiments, 
by Bernard, that the pain produced by section of the fifth 
interfered with the experiment, and that a part of the sensi- 
bility of the facial is derived from a communicating branch 
from the pneumogastric. Bernard exposed the facial, with 
this communicating branch, and found it sensitive ; but af- 
ter division of the branch from the pneumogastric, which 
produced considerable pain, the sensibility of the facial was 
destroyed. 4 

Direct observations upon the properties of the facial as it 
penetrates the auditory canal, and before it has received any 
anastomosing branches from sensitive nerves, must be to a 
certain extent unsatisfactory. All who have experimented 
upon the nerves know that the pain and depression which 
attend so serious an operation as that of exposing the roots 
of a nerve in the cranial cavity are sufficient to render it 
doubtful whether the parts be in a condition to exhibit a 
slight degree of sensibility, which the nerves may possess 
when perfectly normal. Magendie B and Bernard," who have 
exposed the roots of origin of the facial, state unreservedly 
that they are absolutely insensible ; but Longet very justly 

1 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 567. 

2 MAGENDIE, Lefons sur les fonctions et les maladies du systeme nerveux, Paris, 
1841, tome ii., p. 181. 

3 MAGENDIE, op. tit., p. 222. 

4 BERNARD, Lemons sur la physiologic et la pathologic du systeme nerveux, Paris, 
1858, tome ii., p. 28. 

6 MAGENDIE, Systeme nerveux, Paris, 1841, tome ii., p. 208. 
6 BERNARD, Systeme nerveux, Paris, 1858, tome ii., p. 28. 



154 NERVOUS SYSTEM. 

remarks that the conditions under which such observations 
are made have not been, in his hands, sufficiently favor- 
able to admit of a rigorous conclusion on this point. 1 The 
testimony of direct experimentation is in favor of the in- 
sensibility of the* facial at its origin. It is true that the 
intermediary nerve of "Wrisberg has a certain anatomical 
resemblance to the sensitive nerves, chiefly by virtue of its 
ganglioform enlargement ; but direct experiments are want- 
ing to show that it is actually sensitive. In view of this 
fact, it is impossible to reason conclusively from its anatomi- 
cal characters alone. 

The most convenient way to consider the functions of 
the facial will be to take up seriatim the properties and dis- 
tribution of its different branches. 

Functions of the Branches of the Facial within the Aque- 
duct of Fallopius. The first branch, the large petrosal, is 
the motor root of Meckel's ganglion. This will be referred 
to again in connection. with the sympathetic system. The 
second branch, the small petrosal, is one of the motor roots 
of the otic ganglion of the sympathetic. It is thought by 
Longet that this branch simply passes through the ganglion 
to be distributed to the tensor tympani muscle. This au- 
thor regards the small petrosal and the tympanic branch of 
the facial as branches exclusively furnished by the interme- 
diary nerve of Wrisberg, which he considers as the nerve of 
the tympanum, and has called the " tympanic motor nerve." 
This, however, is advanced as a mere supposition, not en- 
tirely proven by experiments. 11 The third branch, the tym- 
panic, is distributed exclusively to the stapedius muscle. 
The second and third branches will be again considered in 
connection with the physiology of the internal ear. 

According to the experiments of Savart, 3 paralysis of the 

1 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 567. 

2 Ibid., p. 579. 

8 SAVART, Recherches sur les usages de la membrane du lympan et de Voreille 
externe. Journal de physiologic, Paris, 1824, tome iv., p. 204. 



FUNCTIONS OF THE CHOKDA TYMPANI. 155 

tensor tympani sliould produce an increased susceptibility 
of the ear to ordinaiy sonorous vibrations. Contrary to 
what might be supposed, it is pretty certain that the mem- 
brane of the tympanum vibrates most intensely when it is 
relaxed, the vibration being much less when it is rendered 
tense by the action of the large muscle of the malleus. This 
view is accepted by Muller, who repeated and extended the 
experiments of Savart. Muller states that this is a physical 
law with regard to membranes of the extent of the tympa- 
num. 1 It is farther carried out by certain cases of paralysis 
of the facial in the human subject, which present, among 
other symptoms, a painful sensibility of the ear to powerful 
impressions of sound. One of the earliest observed and 
most remarkable of these is the case of Prof. Roux, of 
Paris, who suffered from a temporary facial paralysis, and 
who noted that " the membrane of the tympanum was pain- 
fully sensible even to slight noises." a This symptom has 
often been noted in facial palsy. 3 

The fourth branch, the chorda tympani, is so important 
that it demands special consideration. The fifth branch is 
given off opposite to the origin of the chorda tympani and 
passes to the pneumogastric, to which nerve it probably sup- 
plies motor filaments. We have already seen, in studying 
the properties of the roots of the facial, that in this branch, 
sensory filaments pass from the pneumogastric and consti- 
tute a part of the sensory connections of the facial. 4 

Functions of the Chorda Tympani. This branch passes 
between the bones of the ear and through the tympanic cav- 
ity to the lingual branch of the inferior maxillary division 
of the fifth, which it joins at an acute angle, between the 
pterygoid muscles. It has been a question whether this 

1 MI-LLER, Elements of Physiology, London, 1843, vol. ii., p. 1256. 
8 BELL, The Nervous System, London, 1844, p. 329. 

3 BERNARD, Lerons sur la physiologic et la pathologic du systeme ncrvevx, Paris, 
1858, tome ii., p. 114. 

4 See page 153. 



156 NEKVOUS SYSTEM. 

nerve be simply enclosed in the sheath of the lingual branch 
of the fifth or be so closely connected with it that it cannot 
be traced to a distinct distribution. Upon this point we are 
disposed to adopt the opinion of Sappey, who, as the result 
of minute dissections, regards the union as complete, " fibril 
to fibril." As regards the portion of the facial which fur- 
nishes the filaments of the chorda tympani, it is impossible 
to determine anatomically whether these come from the 
main root or from the intermediary nerve of Wrisberg, as 
the fibres of these roots are closely united before the chorda 
tympani is given off. 1 

Concerning the general properties of the chorda tym- 
pani, it is curious to note the opposite opinions of different 
physiologists ; some regarding it as a motor nerve, others 
as purely sensitive, and others as a special nerve of taste. 
When we come to analyze the actual experimental observa- 
tions upon the nerve, it is seen that it cannot be regarded 
as an ordinary motor nerve ; for galvanization of the root 
of the facial before this branch is given off, and careful gal- 
vanization of the chorda tympani itself, produce not the 
slightest movement in the tongue. 2 The operative proced- 
ure necessary to expose the parts is so severe as to render 
observations with regard to its sensibility very unsatisfac- 
tory. It is certain, however, that it is not an acutely sen- 
sitive nerve like the fifth, or like certain branches of the 
pneumogastric. 

The only questions that we propose fo consider in this 
connection relate to the functions of the chorda tympani as 
a nerve of gustation, and as it influences the secretion of the 
submaxillary gland. 

There can be no doubt with regard to the influence of 
the chorda tympani upon the sense of taste in the anterior 
portion of the tongue. "Without citing all of the experi- 
ments and pathological observations bearing upon this ques- 

1 SAPPEY, Traite d'anatomie, Paris, 1852, tome ii., p. 258. 

2 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 581, note. 



FUNCTIONS OF THE CHORDA TYMPANI. 157 

tion, it is sufficient to state, that in cases of disease or injury, 
in which the root of the facial is involved so that the chorda 
tympani is paralyzed, in addition to the ordinary phenom- 
ena of paralysis of the superficial muscles of the face, there 
is loss of taste in the anterior portion of the tongue on the 
side corresponding to the lesion. Numerous cases of this 
kind are quoted in works on physiology, which will be re- 
ferred to more fully in connection with the subject of gus- 
tation. 

In 1863, we had under observation, for several months, 
a soldier who received a gunshot-wound, the ball passing 
through the head, entering just above the ala of the nose 
on the left side and emerging behind the mastoid process 
of the right temporal bone. The wound was nearly healed 
while he was under observation, and the usual symptoms of 
complete facial paralysis were manifested on the right side. 
The buccinator and the orbicularis oculi were completely 
paralyzed. Vision in the right eye was slightly impaired, 
but was improving. The hearing was perfect, and there 
were no abnormal phenomena except those apparently due 
to injury of the facial. The sense of taste was entirely abol- 
ished in the anterior portion of the tongue on the right side. 
Experiments on this point were repeatedly made with salt, 
pepper, and other sapid substances. This patient was ex- 
amined on one occasion by Prof. Dalton, and was exhibited 
in two successive years to the class at the Bellevue Hospi- 
tal Medical College, when the above-mentioned facts were 
verified. 

Physiologists have observed loss of taste in the anterior 
portion of the tongue, in dogs, cats, and other animals, fol- 
lowing section of the root of the facial or of the chorda tym- 
pani. Some observers, it is true, have failed to note the 
phenomena satisfactorily, and there is some difference of 
opinion with regard to the real origin of the gustatory fila- 
ments ; but the fact that the chorda tympani influences the 
taste can hardly be doubted. Adopting this view, w^e shall 



158 NEKVOUS SYSTEM. 

defer the full consideration of the functions of the chorda 
tympani until we come to treat of the special sense of 
taste. 

Schiff, in 1851, was the first to note the influence of the 
chorda tympani upon the secretion of the submaxillary 
gland. In some works on physiology, the experiments of 
Ludwig are referred to as the first upon this subject ; 1 but 
Ludwig only noted the influence upon the salivary secre- 
tion, of filaments going to the submaxillary from the lingual 
branch of the fifth, without experimentally demonstrating 
their real origin. 2 In the experiments of Schiff, the chorda 
tympani was exposed and the flow of the submaxillary saliva 
noted. Upon division of the chorda tympani, the flow of 
saliva was momentarily increased, but was soon arrested ; 
and subsequently, stimulation of the gustatory sense failed 
to induce secretion, as it does when the nerve is intact. 3 
Similar experiments, on a much more extended scale, were 
made by Bernard, in the following way : 

The duct of the submaxillary gland was exposed in a 
dog, and into it was fixed a silver canula. The nervous 
filaments going to the gland from the lingual branch of the 
fifth were then isolated. A little vinegar introduced into 
the mouth caused an abundant flow of saliva from the tube. 
The chorda tympani was then divided, by introducing a 
sharp instrument through the membrane into the tympanic 
cavity. After division of the nerve, the introduction of 
vinegar into the mouth failed to excite the salivary secre- 
tion. From this and similar experiments, Bernard con- 
cludes that the chorda tympani is the motor nerve of the 
submaxillary gland. After having arrested the secretion by 
section of the chorda tympani, the action of the gland was 

1 LONGET, Traite de physiologie, Paris, 1869, tome iii., p. 582. 

8 LUDWIG, Neue Versuche iiber die JBeihilfe der Nerven zur SpelfJidabzon- 
derung. Zdtschrift fur rationette Medicin, Heidelberg, 1851, Neue Folge, Bd. i., 
S. 255, et seq. 

3 SCHIFF, Lemons sur la physiologie de la digestion, Florence et Turin, 1867, 
tome i., p. 217. 



MOVEMENTS OF THE PALATE AND TJTTTLA. 159 

induced by galvanization of the peripheral end of the nerve. 1 
Section of the facial after its passage out of the stylo-mastoid 
foramen did not arrest the action of the parotid ; but section 
of the nerve within the cranium arrested the secretion, both 
of the parotid and submaxillary. 9 

These observations show conclusively that the facial, 
either through branches from its proper roots or its fila- 
ments of communication with other nerves, regulates the 
secretion of at least two of the salivary glands ; a fact to 
which we have already alluded in another volume. 3 

Influence of Various Branches of the Facial upon the 
Movements of the Palate and Uvula. There can be little 
doubt that filaments from the facial animate certain of the 
movements of the velum palati and uvula. It has been ob- 
served that, in certain cases of facial paralysis, the palate 
upon one side is perfectly flaccid and the uvula is drawn to 
the opposite side. Montault * cites a case of this kind, and 
a very striking example is given in full by Bernard ; 6 but 
these phenomena do not occur unless the nerve be affected 
at its root or within the aquseductus Fallopii. It is true 
that the uvula is frequently drawn to one -side or the other 
in persons unaffected with facial paralysis, as was observed 
by Debrou, 6 but it is none the less certain that it is deviated 
as a consequence of paralysis of the facial in some instances.' 
These facts, however, in the absence of direct experiments, 
do not show conclusively that the facial supplies the muscles 
of the seft palate. 

1 BERNARD, Lemons sur la physiologic el la pathologic du systcme nerveux, Paris, 
1858, tome ii., p. 148, et seq. 
8 Op. tit., p. 155. 

3 See vol. in., Secretion, p. 31. 

4 MOXTAULT, Dissertation sur Themiplegiefacialc, These, No. 300, Paris, 1831. 

5 BERNARD, Lecons sur la physiologic et la patJiologie du systeme nerveux, Paris, 
1858, tome ii., p. 133. 

6 DEBROU, Theses dc lecole de medecine, Paris, 1841, No. 266. 
* LOXGET, Traite de physiologic, Paris, 1869, tome iii., p. 576. 

Ill 



160 NERVOUS SYSTEM. 

Direct experiments upon the roots of the facial have not 
been followed by uniform results. Debrou, in the thesis 
just referred to, mentions one experiment in which galvani- 
zation of the facial within the cranial cavity produced de- 
cided contraction of the muscles of the palate ; but in four 
others, the results were negative. Nuhn, however, pro- 
duced contractions of these muscles by galvanization of the 
nerve in the cranium in a man immediately after decapita- 
tion. 1 The experiments of Bernard upon this point are the 
most conclusive ; but while they show, beyond a doubt, that 
the facial animates the movements of the soft palate, they 
do not indicate the course of the filaments from the nerve 
to the muscles. In these experiments, made in connection 
with M. Davaine, the whole of the velum palati was exposed 
in a large-sized dog, by cutting through the hyoid bone. The 
trunk of the glosso-pharyngeal nerve was then exposed in 
the neck, near its point of emergence at the posterior fora- 
men lacerum, and the animal was killed by section of the 
spinal cord just below the origin of the cranial nerves. This 
being done, the glosso-pharyngeal was galvanized, which pro- 
duced violent contractions of the velum, the pillars of the 
fauces, and a part of the pharynx, on one side. The nerve 
was then divided, and the galvanization applied to its pe- 
ripheral end without producing any movement in the velum. 
The central end was then galvanized, when the contractions 
were as vigorous as when the nerve was intact. This result 
would lead to the supposition that contractions of the mus- 
cles of the palate following galvanization of the glosso- 
pharyngeal are reflex and not due to the direct action of 
filaments of distribution from this nerve. In a second ex- 
periment, the parts were exposed in the same way, and, in 
addition, the facial was divided upon the right side at its en- 
trance into the internal auditory canal. The glosso-pharyn- 

1 NUHN, Versuche an einem Eiilhaupteten nebst erlduternden Versuchen an 
Thieren. Zeitschrift fur rationelle Medicin, Heidelberg, 1853, Neue Folge, Bd. 
fii., S. 129, et seq. 



MOVEMENTS OF THE PALATE AND UVULA. 161 

geal nerve was then galvanized upon the side on which the 
fhcial had been divided, with the effect of producing move- 
ments of the pillars of the fauces, but not of the velum palati 
itself. The glosso-pharyngeal was then galvanized upon the 
side on which the facial was intact, which produced move- 
ments of the velum the same as in the first experiment. 
Galvanization of the pneumogastric, the sublingual, and the 
lingual branch of the fifth, failed to produce movements of 
the velum. 

" The first experiment proves that the glosso-pharyngeal 
nerve is not the motor nerve of the velum palati, but that it 
induces reflex movements by the excitation which it trans- 
mits to the nervous centre, an excitation which is carried to 
the parts by another nerve. 

"The second experiment proves that the reflex move- 
ments of the velum palati, induced by the excitation of the 
glosso-pharyngeal,- are in part transmitted by the facial 
nerve, the movements of the pillars not being produced by 
filaments belonging to this nerve." J 

Bernard also noted a fact, which has sometimes been 
observed in cases of facial paralysis, that the point of the 
tongue is deviated after section of the facial ; which is ex- 
plained by the presence of a filament described by Hirsch- 
feld, going from the facial to the tongue. 

As we before remarked, the experiments of Bernard do 
not indicate the mode of communication between the facial 
and the muscles of the palate. Longet regards the filaments 
of the facial which influence the levator palati and azygos 
uvulse muscles as derived from the large petrosal branch 
of the nerve, passing to the muscles through MeckeFs gan- 
glion, the filaments to the palato-glossus and the palato- 
pharyngeus being given off from the glosso-pharyngeal, but 
originally coming from an anastomosing branch of the facial. 
As regards the branches of communication from the glosso- 

1 BERNARD, Lemons sur la pkysiologie et la pathologic du systeme nerveux, Paris, 
1858, tome ii., p. 178. 



i(>2 NERVOUS SYSTEM. 

pharyngeal, Longet mentions a preparation by Richet, in 
the museum of the tiooU de medecine, of Paris, in which 
branches of the facial on one side passed directly to the 
palato-glossus and the palato-pharyngeus without any con- 
nection with the glosso-pharyngeal nerve. 1 In our ana- 
tomical description of the branches of the facial, we have 
already noted a filament, described by Hirschfeld, which 
passes to the stylo-glossus and palato-glossus muscles. 2 
This is the filament affected in deviation of the point of the 
tongue. 

In view of the pathological examples of paralysis of the 
palate and uvula in certain cases of facial palsy, the frequent 
occurrence of contractions of the muscles of these parts upon 
galvanization of the facial, and the reflex action through the 
glosso-pharyngeal and the facial, there can be little doubt 
that the muscles of the palate and uvula are animated by 
filaments derived from the seventh nerve. The effects of 
paralysis of these muscles are manifested by more or less 
difficulty in deglutition and in the pronunciation of certain 
words, with great difficulty in the expulsion of mucus collect- 
ed in the back part of the mouth and the pharynx. These 
points are well illustrated in the case of facial palsy, with 
paralysis of one side of the palate, cited by Bernard. 3 

Functions of the External Branches of the Facial. The 
general function of the branches of the facial going to the 
superficial muscles of the face is sufficiently evident, in view 
of our present knowledge of the distribution of these branch- 
es and the general properties of the nerve. Throughout the 
writings of Sir Charles Bell, the facial is spoken of as the 
" respiratory nerve of the face." It is now recognized as the 
nerve which presides over the movements of the superficial 
muscles of the face, not including those directly concerned 
in the act of mastication. This being its general function, it 

1 LONGET, op. tit., tome ill, p. 581. 2 See page 150. 

3 BERNARD, op. tit., tome ii., p. 133. 



EXTERNAL BRANCHES OF THE FACIAL. 163 

is easy to assign to each of what may be termed the external 
branches of the facial its particular office. 

Just after the nerve has passed out at the stylo-mastoid 
foramen, it sends to the glosso-pharyngeal the communicat- 
ing branch, the functions of which we have just considered 
in connection with the movements of the palate. 

The posterior auricular branch, becoming sensitive by 
the addition of filaments from the cervical plexus, gives sen- 
sibility to the integument on the back part of the ear and 
over the occipital portion of the occipito-frontalis muscle. 
It animates ( the retrahens and the attollens aurem, muscles 
but little developed in man, but very important in certain 
of the inferior animals. It also animates the posterior por- 
tion of the occipito-frontalis muscle. 

The branches distributed to the posterior belly of the 
digastric and to the stylo-hyoid muscle simply animate these 
muscles, one of the uses of which is to assist in deglutition. 
The same may be said of the filaments that go to the stylo- 
glossus. 

The two great branches distributed upon the face after 
the trunk of the nerve has passed through the parotid gland 
have the most prominent function. Both of these branches 
are somewhat sensitive from their connections with other 
nerves, and are distributed in small part to integument. 

The temporo-facial branch animates all of the muscles of 
the upper part of the face. In complete paralysis of this 
branch, the eye is constantly open, even during sleep, from 
paralysis of the orbicularis muscle. In cases of long stand- 
ing, the globe of the eye may become inflamed from con- 
stant exposure, from abolition of the movements of winking 
by which the tears are distributed over its surface and little 
foreign particles are removed, and, in short, from absence 
of the protective action of the lids. In these cases, the lower 
lid may become slightly everted. The frontal portion of the 
occipito-frontalis, the attrahens aurem, and the corrugator 
supercilii muscles, are also paralyzed. The most prominent 



164 NERVOUS SYSTEM. 

symptom of paralysis of these muscles is inability to corru- 
gate the brow upon one side, as in frowning. 

Paralysis of the muscles that dilate the nostrils has been 
shown to have an important influence upon respiration 
through the nose. It was the synchronism between the 
acts of dilatation of the nostrils and the movements of in- 
spiration which first led Sir Charles Bell to regard the facial 
as a respiratory nerve. In instances of complete paralysis 
of the nostril of one side, there is frequently some difficulty 
in inspiration. Sir Charles Bell refers to a case in which, 
when " the patient lay with the sound side against the pil- 
low, he was under the necessity of holding the paralytic 
nostril open with the fingers, in order to breathe freely." 
In the horse, the movements of the nostrils are essential to 
respiration, the animal being unable to breathe through the 
mouth. When both facial nerves are divided in this animal, 
the nostrils collapse and are occluded with each effort at in- 
spiration, and death takes place from suffocation. 3 

Sir Charles Bell 3 and others have also noted the inter- 
ference with olfaction, due to the inability to inhale with 
one nostril, in cases of facial paralysis. The influence of 
the nerve in the act of conveying odorous emanations to 
the olfactory membrane is sufficiently evident after what 
we have remarked concerning the action of the facial in 
respiration. 

The effects of paralysis of the other superficial muscles 
of the face are manifested in the distortion of the features, 
from the unopposed action of the muscles upon the sound 
side ; a phenomenon which is sufficiently familiar to the prac- 

1 BELL, The Nervous System of the Human Body, London, 1844, p. 54. The 
case referred to is No. VI., in the Appendix ; but this seems to be an error, as 
no such circumstance is mentioned in this case. Still the fact illustrated is not 
to be doubted. 

2 BERNARD, Lemons sur la physiologie et la pathologic du systeme nerveux, Paris, 
1858, tome ii., p. 38. 

3 BELL, Of Smelling as influenced by the Portio Dura of the Seventh Ntrve.* 
The Nervous System, London, 1844, p. 134. 



EXTERNAL BRANCHES OF THE FACIAL. 165 

tical physician. When facial palsy affects one side and is 
complete, the angle of the rnouth is drawn to the opposite 
side, the eye upon the affected side is widely and perma- 
nently opened, even during sleep, and the face has upon 
that side a peculiarly expressionless appearance. When a 
patient affected in this way smiles or attempts to grimace, 
the distortion is much increased. The lips are paralyzed 
upon one side, which sometimes causes a flow of saliva- from 
the corner of the mouth. In the lower animals that use 
the lips in prehension, paralysis of these parts interferes 
considerably with the taking of food. The flaccidity of the 
paralyzed lips and cheek in the human subject sometimes 
causes a puffing movement with each act of expiration, as if 
the patient were smoking a pipe. 

We have already seen that the buccinator is not supplied 
by filaments from the nerve of mastication, but is animated 
solely by the facial. Paralysis of this muscle interferes ma- 
terially with mastication, from a tendency to accumulation 
of the food between the teeth and the cheek. Patients 
complain of this difficulty, and sometimes keep the food 
between the teeth by pressure with the hand. In the rare 
instances in which both facial nerves are paralyzed, there is 
very great difficulty in mastication from the cause just men- 
tioned. 

The functions of the external branches of the facial are 
thus sufficiently simple ; and it is only as its deep branches 
affect the taste, the movements of deglutition, etc., that it is 
difficult to ascertain their exact office. As this is the nerve 
of expression of the face, it is in the human subject that 
the phenomena attending its paralysis are most prominent. 
"When both sides are affected, the appearance is most re- 
markable, the face being absolutely expressionless and look- 
ing as if it had been covered with a mask. 



CHAPTER YI. 

SPINAL ACCESSORY AND SUBLINGTJAL NERVES. 

Spinal accessory nerve (third division of the eighth) Physiological anatomy- 
Properties and functions of the spinal accessory Functions of the internal 
branch from the spinal accessory to the pneumogastric Influence of the 
spinal accessory over the vocal movements of the larynx Influence of the 
internal branch of the spinal accessory upon deglutition Influence of the 
spinal accessory upon the heart Functions of the external, or muscular 
branch of the spinal accessory Sublingual, or hypoglossal nerve (ninth) 
Physiological anatomy Properties and functions of the sublingual Glos- 
so-labial paralysis. 

A DESCRIPTION of the properties and functions of the spi- 
nal accessory and the sublingual completes the physiological 
history of the motor nerves emerging from the cranial cav- 
ity. The functions of these nerves are important, and, in 
the case of the spinal accessory, possess considerable inter- 
est, from the fact that physiological investigations have, only 
within a few years, determined the significance of certain of 
its anatomical relations. As we have done in studying the 
other motor nerves, we will treat successively of their ana- 
tomical relations, general properties and functions. 

Spinal Accessory Nerve. (Third Division of the Eighth.) 
The spinal accessory nerve, from the remarkable extent 
of its origin, its important anastomoses with other nerves, 
and its curious course and distribution, has long engaged 
the attention of anatomists and physiologists, who have ad- 
vanced many theories with regard to its office. We will 
content ourselves, however, with a simple description of its 



SPINAL ACCESSORY. 167 

anatomy as it appears from late researches, and will begin 
its physiological history with the comparatively recent ex- 
periments which have advanced our positive knowledge of 
its properties. 

Physiological Anatomy. The origin of this nerve is 
very extensive. A certain portion arises from the lower 
half of the medulla oblongata, and the rest takes its- origin 
below, from the upper two-thirds of the cervical portion of 
the spinal cord. That portion of the root which arises from 
the medulla oblongata is called, by the French, the bulbar 
portion, the roots from the cord constituting the spinal por- 
tion. Inasmuch as there is a marked difference between the 
functions of these two portions, the anatomical distinction 
just mentioned is important. 

The superior roots arise by four or five filaments from 
the lower half of the medulla oblongata below the origin 
of the pneumogastrics. These filaments of origin, in prep- 
arations hardened by prolonged immersion in alcohol, are 
shown to be connected with the lateral portion of the me- 
dulla, and not with the posterior columns. Their origin 
seems, therefore, to be from the motor tract. 1 

The spinal portion of the nerve arises from the upper 
part of the cervical division of the spinal cord, between the 
anterior and posterior roots of the upper four or five cervi- 
cal nerves. The filaments of origin are from six to eight in 
number. The most inferior of these is generally single, the 
other filaments being frequently arranged in pairs. These 
take their origin from the lateral portion of the cord, rather 
nearer the posterior median line than the roots from the 
medulla oblongata. 

Following the nerve from its most inferior filament of 
origin upward, it gradually increases in size by union with 
its other roots, enters the cranial cavity by the foramen 
magnum, and passes to the jugular foramen, by which it 

1 SAPPEY, Traite tfanatomie descriptive, Paris, 1852, tome ii., p. 298. 



168 NERVOUS SYSTEM. 

emerges, in connection with the glosso-phar yngeal, the pneu- 
mogastric, and the internal jugular vein. 

In its course, the spinal accessory anastomoses with sev- 
eral nerves. Just as it enters the cranial cavity, it receives 
filaments of communication from the posterior roots of the 
upper two cervical nerves. These filaments, however, are 
not constant. It frequently, though not constantly, sends a 
few filaments to the superior ganglion, or ganglion of the 
root of the pneumogastric. After it has emerged by the 
jugular foramen, it sends a branch of considerable size to 
the pneumogastric, from which nerve it also receives a few 
filaments of communication. This branch will be again re- 
ferred to in connection with the distribution of the nerve. 
In its course, it also receives filaments of communication 
from the anterior branches of the second, third, and fourth 
cervical nerves. 

In its distribution, the spinal accessory presents two 
branches. The first, or anastomotic branch, passes to the 
pneumogastric just below the plexiform enlargement which 
is sometimes called the ganglion of the trunk of the pneu- 
mogastric. 

The internal, or anastomotic branch, is composed princi- 
pally, if not entirely, of the filaments that take their origin 
from the medulla oblongata. As it joins the pneumogastric, 
it subdivides into two smaller branches. The first of these 
forms a portion of the pharyngeal branch of the pneumo- 
gastric. The second becomes intimately united with the 
pneumogastric, lying at its posterior portion, and furnishes 
filaments to the inferior, or recurrent laryngeal branch, 
which is distributed to all of the muscles of the larynx ex- 
cept the crico-thyroid. The passage of the filaments 'from 
the spinal accessory to the pharyngeal branch of the pneu- 
mogastric is easily observed ; but the fact that filaments 
from this nerve pass to the larynx by the recurrent laryn- 
geal has been ascertained only by physiological experiments. 

The external, or large branch of the spinal accessory, 



SPINAL ACCESSORY. 169 

called the muscular branch, penetrates and passes through 
the posterior portion of the upper third of the sterno-cleido- 
mastoid muscle, goes to the anterior surface of the trape- 
zius, which muscle receives its ultimate branches of distri- 
bution. In its passage through the sterno-cleido-mastoid, 
it joins with branches from the second and third cervical 
nerves, and sends filaments of distribution to the muscle. 
Although the two muscles just mentioned receive numerous 
motor filaments from the spinal accessory, they are also sup- 
plied from the cervical nerves ; and, consequently, they are 
not entirely paralyzed when the spinal accessory is divided. 

Properties and Functions of the Spinal Accessory. Not- 
withstanding the great difficulty in exposing and operating 
upon the roots of the spinal accessory, it has been demon- 
strated that their galvanization produces convulsive move- 
ments in certain muscles. The most satisfactory experi- 
ments with relation to the general properties of the roots 
were made by Bernard. This physiologist cut through 
the occipito-atloid membranes and galvanized the filaments 
within the spinal canal. By galvanizing the filaments aris- 
ing from the medulla oblongata, he produced contractions 
of the muscles of the pharynx and larynx and no move- 
ments of the sterno-mastoid and trapezius. Galvanization 
of the roots arising from the spinal cord produced move- 
ments of the two muscles just mentioned, and absolutely 
no movements in the larynx. 1 Bernard has further shown 
that the roots of the nerve are endowed with recurrent 
sensibility from the posterior roots of the first three pairs 
of cervical nerves. 2 In view of these experiments, it is evi- 
dent that the true filaments of origin of the spinal accessory 
are motor ; and it is further evident that the filaments from 

J BERNARD, Recherche* experimentales sur leg fonctions du nerf spinal, p. 731. 
It is stated in a note that this memoir was printed in the Archives de medecine^ 
in 1844. 

s Loc. cit., p. 730. "We have already fully considered the subject of recur- 
rent sensibility in the anterior roots of the spinal nerves (see page 81). 



1TO NERVOUS SYSTEM. 

the medulla oblongata are distributed to the muscles of the 
pharynx and larynx, while the filaments from the spinal cord 
go to the sterno-cleido-mastoid and trapezius. 

The trunk of the spinal accessory, after the nerve has 
passed out of the cranial cavity, is endowed with a certain 
degree of sensibility. If the nerve be divided, the periph- 
eral extremity manifests the recurrent sensibility, but the 
central end is also sensible, probably from direct filaments 
of communication from the cervical nerves and the pneumo- 
gastric. As we have remarked, however, in treating of the 
properties of some other of the cranial nerves, it is exceed- 
ingly difficult to note satisfactorily a slight degree of sensi- 
bility in nerves that can be exposed only by a tedious and 
painful operation. 

The functions of the external, or muscular branch of the 
spinal accessory are sufficiently evident ; and the effects of 
the destruction of the nerves on both sides, as far as this 
branch is concerned, simply resolve themselves into the 
phenomena due to partial paralysis of the sterno-mastoid 
and trapezius ; but the functions of the branch which joins 
the pneumogastric are much more complex. Without dis- 
cussing the speculative views of the older anatomists and 
physiologists, we will commence with the experiments of 
Bischoff, which were the first to give us any definite ideas 
of the functions of the internal branch. 

Functions of the Internal Branch from the Spinal Acces- 
sory to the Pneumogastric. Bischoff attempted to ascertain 
the functions of this branch by dividing the roots of the 
spinal accessory on both sides in a living animal. The re- 
sults of his experiments may be stated in a very few words. 
He attempted to divide all of the roots of the nerves on 
both sides by dissecting down to the occipito-atloid space 
and penetrating into the cavity of the spinal canal. In the 
first three experiments on dogs, the animals died so soon 
after section of the nerves, that no satisfactory results were 



IXTERXAL BRANCH OF THE SPINAL ACCESSORY. 171 

obtained. In two succeeding experiments on dogs, the ani- 
mals recovered. After division of the nerves, the voice 
became hoarse ; but a few weeks later, became normal. On 
killing the animals, an examination of the parts showed that 
some of the filaments of origin had not been divided. An 
experiment was then made upon a goat, but this was unsat- 
isfactory, as the roots were not completely divided. Finally, 
another experiment was made upon a goat. In this, the 
results were most satisfactory. After division of the nerve 
upon one side, the voice became hoarse. As the filaments 
were divided upon the opposite side, the voice was enfeebled, 
until finally it became extinct. The sound emitted after- 
ward was one which could in nowise be called voice, "qui 
neutlqi.iam vox appellari potuit" 1 This experiment was 
made in the presence of Tiedemann and Seubertus, and was 
not repeated. 

It is evident to any one familiar with the elaborate re- 
searches of Bernard upon the spinal accessory, that it was 
only necessary to confirm the single successful experiment 
of BischofF to settle the fact of the influence of this nerve 
upon phonation. The great difficulty of the operative pro- 
cedure, however, prevented its repetition on an extended 
scale. Longet, in 1841,* published an account of some ex- 
periments confirming, to a certain extent, those of Bischoif; 
but in his treatise on the nervous system, published in 1842,* 
he does not seem to regard the spinal accessory as the exclu- 
sive nerve of phonation, as he does in his work on physi- 
ology, published after the experiments of Bernard. 4 The 
results of the experiments performed at this time by Longet 

1 BISCHOFF, Nervi Accessorii Willisii Anatomia et Physiologia, Darmstadii, 
1832, p. 94. 

s LOXGET, Recherches experimentalts sur les fonctions des nerfs, dcs muscles du 
larnyx et sur F influence du nerf accessoire de Willis dan* la phonation. Gazette 
mcdicale, Paris, 1841, 2eme serie, tome ix., p. 472. 

3 LOXGET, Anatomic et physiologic du systeme nerveux, Paris, 1842, tome ii., 
p. 263. 

4 LOXGET, Trait* de pfiysiologie, Paris, 1869, tome iii., p. 516. 



172 NERVOUS SYSTEM. 

were by no means so satisfactory as tlie single successful ob- 
servation of Bisclioif. In his memoir on the spinal acces- 
sory, Bernard gives full credit to Bischoff, and quotes from 
this author the very words we have just cited. "With regard 
to the question of priority in the description of the function 
of this nerve in phonation, there can be no doubt concern- 
ing the accuracy of the experiment of Bischoff and its correct 
interpretation, in 1832. He demonstrated that the nerve 
presiding over the voice is the spinal accessory ; although 
the fact rested on a single successful experiment, and was 
not accepted by physiologists before it had been fully con- 
firmed by the repeated and conclusive experiments of Ber- 
nard, made by an entirely different method. To Bernard, 
however, remains, as we shall presently see, the merit of 
having demonstrated that the vocal muscles are supplied 
by those filaments of the spinal accessory that take their 
origin from the medulla oblongata. 

Bernard, whose ingenious experiments determined ex- 
actly the influence of the spinal accessory over the vocal 
movements of the larynx, first repeated the experiments 
of Bischoff; but the animals operated upon died so soon, 
from hsemorrhage, or other causes, that his observations 
were not satisfactory. 1 After many unsuccessful trials, he 
succeeded in overcoming all difficulties, by following the 
trunk of the nerve back to the jugular foramen, seizing 
it here with a strong pair of forceps, and drawing it out 
by the roots. 2 This operation is difficult, but we have sev- 

1 BERNARD, Recherches experimentales sur lesfonctions du nerf spinal, p. 733. 
Bernard considers that death is due after this operation, as performed by Bis- 
choff, to the passage of air into the veins. 

8 The operative procedure employed by Bernard is the following: The 
trunk of the nerve is exposed as it passes through the sterno-cleido-mastoid 
muscle. It is then followed up by careful dissection, avoiding blood-vessels as 
much as possible, to the posterior foramen lacerum, when the sublingual is seen 
crossing the course of the pneumogastric. It is here that the anastomotic 
branch leaves the spinal accessory to go to the pneumogastric. At this point, 
the external branch, with the anastomosing branch, is seized with a pair of 
rather broad-billed forceps, and gentle but firm traction is applied to the entire 



INTERNAL BRANCH OF THE SPINAi ACCESSORY. 173 

eral times performed it with entire success, and verified, in 
every regard, the facts observed by Bernard. Within the 
last year, the excellent assistant to the chair of Physiology 
at the Bellevue Hospital Medical College, Dr. C. F. Koberts, 
has succeeded in extirpating these nerves for class-demonstra- 
tions. The operation is generally most successful in cats, 
though Bernard has succeeded frequently in other animals. 

When one spinal accessory is extirpated, the vocal sounds 
are hoarse and unnatural. When both nerves are torn out, 
in addition to the disturbance of deglutition and the partial 
paralysis of the sterno-mastoid and trapezius muscles, the 
voice becomes extinct. Animals operated upon in this way 
move the jaws and make evident efforts to cry, but no vocal 
sound is emitted. This condition is very striking ; and in- 
asmuch as Bernard has kept animals, with both nerves ex- 
tirpated, for months, the question of the function of these 
nerves in phonation may now be regarded as definitively 
settled. 

It remains now to consider the experimental facts with 
regard to the influence of the different filaments of origin 
of the spinal accessory on the voice. These are simple, and 
entirely conclusive ; and they are due exclusively to the re- 
searches of Bernard. This experimenter found that division 
of the roots of origin from the spinal cord not only did not 
affect the voice, but sometimes seemed to render it clearer ; 
but that division of the roots of origin from the medulla ob- 
longata abolished the voice, though the inferior roots were 
intact. 1 

It is not necessary to discuss the action of the muscles 
of the larnyx in phonation, as this subject has already been 
considered in full in another volume. 3 The beautiful experi- 

nerve. Soon there is a cracking sensation conveyed to the hand as the roots 
give way, and the nerve may then be drawn out entire. With care, either the 
filaments of origin from the medulla or those from the cord may be extirpated 
alone. (BERNARD, op. cit., p. 736 ; and, Lemons sur la physiologic et la pathologic 
du sysleme nerveux, Paris, 1858, tome ii., p. 296.) 

1 Op. cit., p. 735. s See vol. i., Voice and Speech, p. 490, et seq. 



NEKVOUS SYSTEM. 

ments tliat have demonstrated the influence of the spinal 
accessory nerve over these muscles have pointed out the des- 
tination of the fibres that join the pneumogastric, which could 
never have been done so satisfactorily by dissection. They 
have shown further that the movements involved in phona- 
tion are more or less independent of the respiratory move- 
ments of the larnyx. 

If the larnyx be exposed in a living animal, with all its 
nervous connections intact, it w r ill be seen to open widely 
during inspiration, being passive in expiration. The wide 
opening of the glottis at this time is due to the fact that, 
after the operation, respiration is usually more or less la- 
bored ; but if we carefully observe the parts when the respira- 
tory acts are perfectly tranquil, the movements of the glottis 
seem to be very slight. The larynx is then permanently 
opened to a moderate degree, but the chink of the glottis is 
slightly dilated with each expiration. If the recurrent laryn- 
geal nerves, which are distributed to all of the muscles of 
the larynx except the crico-thyroid, be now divided upon 
both sides, the larynx is entirely paralyzed, and in cats and 
young animals, in which the cartilages are soft and flexible, 
the parts are occluded by the effort of inspiration, and death 
takes place from suffocation. Of course the division of the 
recurrent laryngeal nerves abolishes the voice, but it arrests 
the other movements of the larynx as well. The distinction 
thus established between the action of the spinal accessory 
and the recurrent laryngeal nerves was fully illustrated by 
Bernard, in the following experiments : 

In a cat, in which the voice had been completely de- 
stroyed by extirpation of both spinal accessory nerves, the 
larynx was exposed. The glottis was seen dilated so as to 
permit the free passage of air in respiration. The mucous 
membrane retained its sensibility, and when the interior of 
the larynx was irritated, a very slight but ineffectual effort 
was made to close the glottis. It was impossible for the 
animal to approximate the posterior points of attachment of 



INTERNAL BRANCH OF THE SPINAL ACCESSORY. 175 

the vocal cords, or to put the cords on the stretch. If such 
irritation be applied to the larynx of an animal wi'th the 
spinal accessory nerves intact, the glottis is instantly and 
firmly closed. 1 

In a cat about five weeks old, both spinal accessory 
nerves were extirpated, and the voice was thus destroyed. 
Two days after, both recurrent laryngeal nerves were di- 
vided, and the animal died almost immediately of suffo- 
cation. 2 

These experiments show conclusively that the internal, 
or communicating branch of the spinal accessory is the 
nerve which presides over the movements of the larynx in 
phonation. The filaments undoubtedly pass to the larynx 
in greatest part through the recurrent laryngeal branches of 
the pneumogastric ; but the recurrent laryngeals also con- 
tain motor filaments from other sources, which are chiefly 
concerned in the respiratory movements of the glottis. 

Influence of the Internal Branch of the Spinal Accessory 
upon Deglutition. We must refer again to the experiments 
of Bernard for an account of the influence of the spinal 
accessory upon deglutition. There are two ways in which 
deglutition is affected through this nerve: 1. When the 
larynx is paralyzed as a consequence of extirpation of both 
nerves, the glottis cannot be completely closed to pre- 
vent the entrance of foreign bodies into the air-passages. 
In rabbits particularly, it was rioted that particles of food 
penetrated the trachea and found their way into the lungs. 3 
2. The spinal accessory furnishes numerous filaments to the 
pharyngeal branch of the pneumogastric, and, through this 
nerve, directly affects the muscles of deglutition ; but the 
muscles animated in this way by the spinal accessory have a 

1 BERNARD, op. 7., p. 745. 
8 Loc. tit., p. 749. 

3 BERNARD, Lemons sur la physiologic et la pathologie d*. systbne nervevx, 
Paris, 1858, tome ii., p. 323. 
112 



176 NERVOUS SYSTEM. 

tendency to draw the lips of the glottis together, while they 
assist in passing the alimentary bolus into the oesophagus. 
When these important acts are wanting, there is some diffi- 
culty in the process of deglutition itself as well as danger of 
the passage of alimentary particles into the larynx. 

Influence of the Spinal Accessory upon the Heart. 
When we come to study the varied functions of the pneumo- 
gastrics, we will discuss fully the mechanism by which the 
contractions of the heart are arrested by galvanization of both 
of these nerves in the neck. A very curious and interesting 
observation by Waller has demonstrated that this influence, 
whatever be its mechanism, is derived from the spinal acces- 
sory, and necessarily comes through its communicating 
branch. It has been found that a powerful current of gal- 
vanism passed through the pneumogastric on one side will 
arrest the action of the heart. Waller found that if he ex- 
tirpated the spinal accessory on one side, the action of the 
heart could not be arrested by galvanizing the pneumo- 
gastric upon the same side ; but this result followed gal- 
vanization of the pneumogastric upon the opposite side, on 
which the connections with the spinal accessory were intact. 
These phenomena, however, could not be observed until 
from ten to twelve days had elapsed after the extirpation of 
the spinal accessory. 1 We have already seen, in treating of 
the general properties of the nerves, that the irritability of 
the motor nerves disappears in about four days after their 
separation from the nerve-centres. 2 In the observation just 
referred to, it seemed necessary that a sufficient time should 
elapse after extirpation of the spinal accessory for the irrita- 

1 WALLER, Experiences sur les nerfs pneumogastriques et accessoires de Willis. 
Gazette medicate, Paris, 1856, 3eme serie, tome xi., p. 420. 

In these experiments, Waller demonstrated by microscopical examination 
the disorganization of both "branches of the spinal accessory, and showed that 
their galvanization produced little, if any contraction in the muscles to which 
these branches were distributed. 

3 See p. 96u 



EXTERNAL BRANCH, OF THE SPINAL ACCESSORY. 177 

bility of the filaments that join the pneumogastric to become 
extinct ; but the experiment is sufficient to show the direct 
inhibitory influence of the spinal accessory on the heart. 
The subject will be more fully considered, however, in con- 
nection with the functions of the pneumogastrics. 

Functions of the External, or Muscular Branch of the 
Spinal Accessory. The most interesting feature ' in the 
recent researches into the functions of the spinal accessory 
is, that experimentalists have been able to separate physio- 
logically the internal from the external branch. Observa- 
tions have conclusively demonstrated that the internal 
branch, and the internal branch only, is directly concerned 
in the vocal movements of the larynx, and, to a great ex- 
tent, in the closure of the glottis during deglutition. It has 
been noted, in addition, that animals in which both branches 
have been extirpated present irregularity of the movements 
of the anterior extremities and suffer from shortness of 
breath after violent muscular exertion. The use of the cor- 
responding extremities in the human subject is so different, 
that it is not easy to make a direct application of these ex- 
periments ; still, we can draw from them certain inferences 
with regard to the functions of the external branch in man. 

In prolonged vocal efforts, the vocal cords are put upon 
the stretch, and the act of expiration is very different from 
that in tranquil breathing. In singing, for example, the 
shoulders are frequently fixed ; and this is done to some ex- 
tent by the action of the sterno-cleido-mastoid and the trape- 
zius. "We may suppose, then, that the action of the branch 
of the spinal accessory which goes to these muscles has a cer- 
tain synchronism with the action of the branch going to the 
larynx and the pharynx ; the one fixing the upper part of 
the chest so that the expulsion of the air through the glottis 
may be more nicely regulated by the expiratory muscles, 
and the other acting upon the vocal cords. 1 

1 It is unnecessary to make any further reference in detail to the admirable 



178 NERVOUS SYSTEM. 

In what is known to physiologists as muscular effort, the 
mechanism of which has been discussed in another volume, 1 
the glottis is closed, the thorax is fixed after a full inspira- 
tion, and respiration is arrested so long as the effort, if it be 
not too prolonged, is continued. The same synchronism, 
therefore, obtains in this as in prolonged vocal efforts. In 
experiments in which the muscular branch only has been 
divided, shortness of breath, after violent muscular effort, is 
observed; and this is probably due to the want of syn- 
chronous action of the sterno-cleido-mastoid and trapezius. 
The irregularity in the movements of progression in 
animals, in which either both branches or the muscular 
branches alone have been divided, is due to anatomical 
peculiarities. Bernard has observed these irregularities in 
the dog and the horse, but they are not so well marked in 
the cat. There have been no opportunities for illustrating 
these points in the human subject. 

Sublingual) or Hypoglossal Nerve (NiniK). 

The last of the motor cranial nerves is the sublingual ; 
and its functions are intimately connected with the physi- 
ology of the tongue in deglutition and articulation, though 
it is also distributed to certain of the muscles of the neck. 

Physiological Anatomy. The apparent origin of the sub- 
lingual is from the medulla oblongata, in the groove between 
the olivary body and the anterior pyramid, on the line of the 
anterior roots of the spinal nerves. At this point, its root is 
lormed of from ten to twelve filaments, which extend from, 
the inferior portion of the olivary body to about the junction 
of the upper with the middle third. These filaments of 
origin are separated into two groups, superior and inferior. 
From this apparent origin, the filaments have been traced 

memoir of Bernard on the spinal accessory, in which the function of the ex- 
ternal branch in the lower animals has been fully investigated by experiments. 
1 See vol. Hi., Movements, p. 477. 




SUBLINGTJAL NEEVE. 179 

> 

into the gray matter of the floor of the fourth ventricle, be- 
tween the deep origin of the pneumogastric and the glosso- 
pharyngeal. Though there is much difference of opinion 
upon this point, it is probable, from the elaborate researches 
of Dr. Dean, 1 that some of the filaments of origin of these 
nerves decussate in the floor of the fourth ventricle. 

The superior and inferior filaments of origin of the nerve 
unite respectively to form two bundles, which pass through 
distinct perforations in the dura mater. These two bundles 
then pass into the anterior condyloid foramen, and unite into 
a single trunk as they emerge from the cranial cavity. In 
some of the inferior animals, the calf, horse, pig, rabbit, dog, 
and cat, there is a delicate filament arising from the latero- 
posterior portion of the medulla, remarkable by the presence 
of a small ganglion, which joins the trunk of the nerve as it 
passes through the foramen. This was described by Mayer, 
and more lately by Yulpian ; both of these observers having 
noted it exceptionally in the human subject. 8 Direct experi- 
ments are wanting to show positively the physiological prop- 
erties of this ganglionic root. 

After the sublingual has passed out of the cranial cavity, 
it anastomoses with several nerves. It sends a filament of 
communication to the sympathetic as it branches from the 
superior cervical ganglion. Soon after it has passed through 
the foramen, it sends a branch to the pneumogastric. It 
anastomoses by two or three branches with the upper two 
cervical nerves, the filaments passing in both directions be- 
tween the nerves. It anastomoses with the lingual branch of 
the fifth, by two or three filaments passing in both directions. 

In its distribution, the sublingual presents several re- 
markable peculiarities. 

Its first branch, the descendens noni, passes down the 

1 DEAN, The Gray Substance of the Medulla Oblongata and Trapezium, Wash- 
ington, 1864, p. 16. 

8 VULPIAH, Sur la racine posterieure ou ganglionnaire du nerf hypoglosse. 
Journal de la physiologic, Paris, 1862, tome v., p. 5, et seq. 



180 NERVOUS SYSTEM. 

neck to the sterno-hyoid, sterno-thyroid, and omo-hyoid 
muscles. From its relations with important vessels and 
nerves, this branch possesses considerable surgical interest. 

The thyro-hyoid branch is distributed to the muscle of 
the same name. 

The other branches are distributed to the stylo-glossus, 
hyo-glossus, genio-hyoid, and genio-hyo-glossus muscles, their 
terminal filaments going to the intrinsic muscles of the tongue. 

It is thus seen that the sublingual nerve is distributed to 
all of the muscles in the infra-hyoid region, the action of 
which is to depress the larynx and the hyoid bone after the 
passage of the alimentary bolus through the pharynx ; to one 
of the muscles in the supra-hyoid region, the genio-hyoid ; 
to most of the, muscles which move the tongue ; and to the 
muscular fibres of the tongue itself. The action of these 
muscles and of the tongue itself in deglutition has already 
been fully discussed in another volume. 1 

Properties and Functions of the Sublingual. There is 
every reason to believe that the sublingual nerve is entirely 
insensible at its origin from the medulla oblongata. The 
fact that it arises from a continuation of the motor tract 
of the spinal cord and has no ganglion upon its main 
.root would lead to the supposition that it is an exclusively 
motor nerve. In operating upon the roots of the spinal 
accessory, when the origin of the sublingual is necessarily 
exposed, Longet has irritated the roots in the dog without 
any evidence of pain on the part of the animal. 2 In the dog, 
Yulpian has constantly found the small ganglionic root, 3 
which we have already mentioned as exceptional in the hu- 
man subject. Such experiments, taken in connection with 
the anatomical characters of the nerve, render it almost cer- 

1 See vol. ii., Digestion, p. 189, el seq. 

2 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 584. 

8 VULPIAN, Sur la racine posterieure ou ganglionnaire du nerf hypoglosse. 
Journal de la physiologic, Paris, 1862, tome v., p. 7. 



STJBLINGUAL NERVE. 181 

tain that the main root is devoid of sensibility. They do 
not, however, positively demonstrate the insensibility of the 
ganglionic root, for a severe operation, it is well known, may 
temporarily abolish the sensibility of nerves when this is not 
very acute, as is seen in experiments upon the recurrent sen- 
sibility of the anterior roots of the spinal nerves. Still, as 
this filament is ordinarily absent in the human subject, there 
can be little doubt that the sublingual at its origin js exclu- 
sively motor. 

All modern experimenters have confirmed the observa- 
tions of Mayo 1 and of Magendie, 2 with regard to the sensi- 
bility of the sublingual after it has passed out of the cranial 
cavity. The anastomoses of this nerve with the upper two 
cervical nerves, the pneumogastric, and the lingual branch 
of the fifth, afford a ready explanation of this fact. Accord- 
ing to Bernard, this nerve possesses recurrent sensibility de- 
rived from the fifth pair. 8 

The functions of the sublingual have already been so 
fully considered under the head of deglutition, that they 
need not be discussed elaborately in this connection. We 
will here simply state the phenomena which follow stimula- 
tion of the nerve and the division of both nerves in living 
animals. 

The sublingual may be easily exposed in the dog by 
making an incision just below the border of the lower jaw, 
dissecting down to the carotid artery, and following the ves- 
sel upward until we see the nerve as it crosses its course. 
On applying a feeble current of galvanism at this point, 
there are evidences of sensibility, and the tongue is moved 
convulsively at each stimulation. 

The phenomena following section of both sublingual 

1 MAYO, Anatomical and Physiological Commentaries, Number ii., London, 
1823, p. 11. 

8 MAGENDIE, Lecons sur les functions et les maladies du systeme nerveux, Paris, 
1841, tome ii., p. 290. 

3 BERNARD, Lecons sur la physiologic et la pathologic du systeme nerveux, Paris, 
1858, tome ii., p. 241. 



182 NERVOUS SYSTEM. 

nerves point directly to their function. The most notable 
fact observed after this operation is, that the movements of 
the tongue are entirely lost, while the tactile and gustatory 
senses are not affected. These phenomena have been accu- 
rately described by Mayo, 1 Panizza, 3 Magendie, 3 and many 
others. Perhaps the most varied experiments made upon 
animals are those of Panizza. These have been fully detailed 
in connection with the subjects of mastication and degluti- 
tion. They consist simply in loss of power over the tongue, 
with considerable difficulty in deglutition. We have repeat- 
edly noted all of these points and demonstrated them to 
medical classes. 

In the human subject, the sublingual is usually more or 
less affected in hemiplegia. In these cases, as the patient 
protrudes the tongue, the point is deviated. This is due to 
the unopposed action of the genio-hyo-glossus upon the sound 
side, which, as it protrudes the tongue, directs the point 
toward the side affected with paralysis. 

A disease of rather rare occurrence has lately been de- 
scribed under the name of glosso-labial paralysis, which is 
characterized by paralysis of the sublinguals, affecting also 
the orbicularis oris, and frequently the intrinsic muscles of 
the larynx. The phenomena referable to the loss of power 
over the tongue correspond to those observed in animals 
after section of the nerves. Patients affected in this way 
experience difficulty in deglutition, and, in addition, we note 
an interference with articulation, which cannot be observed 
in experiments upon animals. "We lately had a case of this 
disease under observation in the Bellevue Hospital, the phe- 
nomena of which were peculiarly interesting from a physio- 
logical point of view. This patient presented complete 
paralysis of the tongue, with considerable difficulty in deglu- 
tition, probably from the tongue-affection. The orbicularis 

1 Loc. cit. 

2 PANIZZA, Nouvelles recherches experimentales sur les nerfs. Gazette medicate, 
Paris, 1835, p. 419. 3 j^ ^ 



SUBLLXGUAL NERVE. 



183 



oris was also paralyzed. The paralysis probably extended 
to the intrinsic muscles of the larynx, as little or no vocal 
sound could be made. The patient was incapable of articu- 
late language, and communicated entirely by signs. 



MEDICAL 

LIBRARY. 




CHAPTER VII. 

TRIFACIAL, OR TRIGEMINAL NERVE. 

Physiological anatomy of the trifacial Properties and functions of the trifacial 
Division of the trifacial within the cranial cavity Immediate effects of 
division of the trifacial Remote effects of division of the trifacial Effects 
of division of the trifacial upon the organs of special sense Division of the 
trifacial before and behind the ganglion of Gasser Communication with 
the sympathetic at the ganglion of Gasser Explanation of the phenomena 
of disordered nutrition after division of the trifacial Cases of paralysis of 
the trifacial in the human subject. 

A SINGLE nerve, the large root of the fifth pair, called 
the trifacial, or the trigeminal, gives general sensibility to 
the face and the head as far back as the vertex. This is one 
of the most interesting of the cranial nerves, and is one of 
the first that was experimented upon by physiologists. It 
is interesting, not only as the great sensitive nerve of the 
face, but from its connections with other nerves and its re- 
lations to the organs of special sense. In studying the 
physiology of this nerve, we must necessarily begin with its 
physiological anatomy. 

Physiological Anatomy. The apparent origin of the 
large root of the fifth is from the lateral portion of the pons 
Yarolii, posterior and inferior to the origin of the small root, 
from which it is separated by a few transverse fibres of white 
substance. The deep origin is far removed from its point of 
emergence from the encephalon. The roots pass entirely 
through the substance of the pons, from without inward and 
from before backward, without any connection with the 
fibres of the pons itself. By this course it reaches the me- 



TRIFACIAL NERVE. 185 

dulla oblongata, where the roots divide into three bundles. 
The anterior bundle passes from behind forward, between 
the anterior fibres of the pons and the cerebellar portion of 
the restiform bodies, to anastomose with the auditory nerve. 1 
The other bundles, which are posterior, pass, the one in the 
anterior wall of the fourth ventricle to the lateral tract of the 
medulla oblongata, and the other, becoming grayish in color, 
to the restiform bodies, from which they may be followed as 
far as the point of the calamus scriptorius. According to 
Yulpian, a few fibres from the two sides decussate in the 
median line in the anterior wall of the fourth ventricle. 2 

From this origin, the large root of the fifth passes ob- 
liquely upward and forward to the ganglion of Gasser, 
which is situated in a depression in the petrous portion of 
the temporal bone on the internal portion of its anterior 
face. 

The Gasserian ganglion is semilunar in form (sometimes 
it is called the semilunar ganglion), with its concavity looking 
upward and inward. 3 At the ganglion, the nerve receives 
filaments of communication from the carotid plexus of the 
sympathetic. This anatomical point is of importance in view 
of some of the remote effects which follow division of the 
fifth nerve through the ganglion in living animals. 

It will be necessary only to describe in a general way 



HIRSCHFELD, Systeme nerveux, Paris, 1866, p. 166. The anastomo- 
sis of the auditory nerve has been denied (VFLPIAN, Essai sur Forigine de 
plusieurs paires des nerfs craniens, These, Paris, 1853, p. 27), but it is admitted 
by most anatomists. 

2 Op. tit., p. 25. 

3 The structure of this ganglion was first recognized by Gasser, Professor of 
Anatomy in Vienna. His observations, however, were published by Hirsch, a 
pupil of Gasser, in 1765 (HiRSCH, Paris quinti Nervorum encephali, Vienme, 
1765, hi LUDWIG, Scriptores Nevrologiti minores selecti, Lipsiae, 1791, tomus i., p. 
244, et seq.). Hirsch first gave it the name of Gasserian ganglion (p. 262). 
Some authors call it the Casserian ganglion, probably confounding Gasser with 
Casserius. Casserius, in his anatomical figures, describes many parts of the 
brain and nerves, but says nothing of the gangh'on of the fifth (CASSERIUS, 
Anatormche Tafeln, Franckfurt am Mayn, 1756). 



186 NERVOUS SYS'LEM. 

the numerous branches of distribution of the fifth nerve, 
remembering that it is the great sensitive nerve of the 
face. 

At the ganglion of Gasser, from its anterior and external 
portion, are given off a few small and unimportant branches 
to the dura mater and tentorium. 

From the convex border of the ganglion, the three great 
branches arise that have given to the nerve the name of 
trifacial or trigeminal. These are: 1, the ophthalmic; 2, 
the superior maxillary ; 3, the inferior maxillary. The oph- 
thalmic and the superior maxillary branch are derived en- 
tirely from the sensory root. The inferior maxillary branch 
joins with the motor root and forms a mixed nerve. 

The ophthalmic branch, the first division of the fifth, is 
the smallest of the three. Before it enters the orbit, it re- 
ceives filaments of communication from the sympathetic, 
sends small branches to all of the motor nerves of the eye- 
ball, and gives off a small recurrent branch which passes be- 
tween the layers of the tentorium. 

Just before the ophthalmic branch enters the orbit by 
the sphenoidal fissure, it divides into three branches ; the 
lachrymal, frontal, and nasal. 

The lachrymal, the smallest of the three, sends a branch 
to the orbital branch of the superior maxillary nerve, passes 
through the lachrymal gland, to which certain of its fila- 
ments are distributed, and its terminal filaments go to the 
conjunctiva and the integument of the upper eyelid. 

The frontal branch, the largest of the three, divides into 
the supra-trochlear and supra-orbital nerves. The supra- 
trochlear passes out of the orbit between the supra-orbital 
foramen and the pulley of the superior oblique muscle. It 
sends in its course a long, delicate filament to the nasal 
branch, and is finally lost in the integument of the forehead. 
The supra-orbital passes through the supra-orbital foramen, 
sends a few filaments to the upper eyelid, and supplies the 
forehead, the anterior and median portions of the scalp, the 



TEIFACIAL NERVE. 187 

mucous membrane of the frontal sinus, and the pericranium 
covering the frontal and 'parietal bones. 

The nasal branch, before it penetrates the orbit, gives off 
a long, delicate filament to the ophthalmic ganglion, consti- 
tuting its sensory root. It then gives off the long ciliary 
nerves, which pass to the ciliary muscle and iris. Its trunk 
then divides into the external nasal, or infra-trochlearis, and 
the internal nasal, or ethmoidal. The infra-trochlearis is dis- 
tributed to the integument of the forehead and nose, to the 
internal surface of the lower eyelid, the lachrymal sac, and the 
caruncula. The internal nasal is distributed to the mucous 
membrane, and also in part to the integument of the nose. 

The superior maxillary branch of the fifth passes out of 
the cranial cavity by the foramen rotundum, traverses the 
infra-orbital canal, and emerges upon the face by the infra- 
orbital foramen. Branches from this nerve are given off in 
the spheno-maxillary fossa and the infra-orbital canal, before 
it emerges upon the face. In the spheno-maxillary fossa, the 
first branch is the orbital, which passes into the orbit, giving 
off one branch, the temporal, which passes through the tem- 
poral fossa by a foramen in the malar bone, and is distrib- 
uted to the integument on the temple and the side of the 
forehead ; another branch, the malar, which likewise emerges 
by a foramen in the malar bone, is distributed to the in- 
tegument over this bone. In the spheno-maxillary fossa, 
are also given off two branches, which pass to the spheno- 
palatine, or Heckel's ganglion. From this portion of the 
nerve, branches are given off, the two posterior dental nerves, 
which are distributed to the molar and bicuspid teeth, the 
mucous membrane of the corresponding alveolar processes, 
and to the antrum. 

In the infra-orbital canal, a large branch, the anterior 
dental, is given off to the teeth and mucous membrane of the 
alveolar processes not supplied by the posterior dental nerves. 
This nerve anastomoses with the posterior dental. 

The terminal branches upon the face are distributed to 



188 NERVOUS SYSTKM. 

the lower eyelid (the palpebral brandies) ; to the side of the 
nose (the nasal branches), anastomosing with the nasal 
branch of the ophthalmic ; and to the integument and mu- 
cous membrane of the upper lip (the labial branches). 

The inferior maxillary is a mixed nerve, composed of the 
inferior division of the large root and the small root. The 
distribution of the motor filaments has already been de- 
scribed under the head of the nerve of mastication. 1 This 
nerve passes out of the cranial cavity by the foramen ovale, 
and then separates into the anterior division, containing 
nearly all of the motor filaments, and the posterior division, 
which is chiefly sensory. The sensory portion breaks up 
into numerous branches : 

1. The auriculo-temporal nerve supplies the integument 
in the temporal region, the auditory meatus and the integu- 
ment of the ear, the temporo-maxillary articulation, and the 
parotid gland. It also sends important branches of commu- 
nication to the facial. 

2. The lingual branch is distributed to the mucous mem- 
brane of the tongue as far as the point, the mucous mem- 
brane of the mouth, the gums, and to the sublingual gland. 
This nerve receives an important branch from the facial, the 
chorda tympani, which has already been described. 9 From 
this nerve, also, are given off two or three branches which pass 
to the submaxillary ganglion, constituting its sensory roots. 

3. The inferior dental nerye, the largest of the three, 
passes in the substance of the inferior maxillary bone, be- 
neath the teeth, to the mental foramen, where it emerges 
upon the face. The most important sensory branches are 
those which supply the pulps of the teeth, and the branches 
upon the face. The nerve, emerging upon the face by the 
mental foramen, called the mental nerve, supplies the integ- 
ument of the chin and the lower part of the face, the lower 
lip, and sends certain filaments to the mucous membrane of 
the mouth. 

1 See page 141. 8 See page 143. 



TEIFAC1AL NEEV1 .. 139 

Properties and Functions of the Trif octal. Our definite 
knowledge with regard to the properties and functions of the 

e root of the fifth nerve dates from the experiments by 
Mayo, published in 1822. It is generally stated by authors 
that the researches of Sir Charles Bell, in 1811, led natural- 

. the idea that the ganglionic root of the fifth was entire- 
ly nensory. We have already shown, by full references to 
the paper printed by Sir Charles Bell, in 1811, that he there- 
in attributed both motion and sensation to the anterior roots 
of the spinal nerves, regarding the ganglionic roots as nerves 
presiding over the functions of organic life. 1 The mistake 
made by authors in attributing the exact distinction between 
the functions of the large root of the fifth and the small root 
and the facial arises from the fact that a paper published 
originally in the Philosophical Transactions, in 1821, 2 is re- 
printed with other memoirs, "with some additional explana- 
tions." ! The additions to the original paper are in such a 
form as to lead the reader to suppose that the author regard- 
ed the large root of the fifth as exclusively sensory; but, in 
the original paper, which we have carefully compared with 
the reprint, the distinction between the motor and the sen- 
sory root of the fifth is by no means clearly made. 

In 1822, Herbert Mayo published an account of " experi- 
ments to determine the influence of the portio dura of the 
seventh, and of the facial branches of the fifth pair of nerves." 
These experiments consisted in dividing the infra-orbital, in- 
ferior maxillary, and frontal branches of the fifth, and the 
branch from the fifth to the seventh, in asses, by which 
it was demonstrated that these were exclusively sensory 
nerves. 4 In a second publication, the following year, it is 

1 See page 71. 

<J JiKi.L, On tJie Nerves ; giving an Account of some Experiments on their 
Structure and Functions, which lead to a New Arrangement of t/ie System. 
riuloHophical Transactions, London, 1821, Part i., p. 398. 

3 BELL, The Nervous System of the Human Body, as explained in a Series 
of Papers read before the Royal Society of London, London, 1844, p. 33. 

4 MAYO, Anatomical and Physiological Commentaries, Number i., London, 
1822, p. 107, et seq. 



190 NEBVOUS SYSTEM. 

stated that the root of the fifth was divided in the cranial 
cavity in pigeons ; 1 but this was with reference chiefly to the 
movements of the iris, though Mayo notes that after division 
of the nerve " the surface of the eyeball appears to have lost 
its feeling." 

In 1823, Fodera published an account of experiments in 
which he had divided the roots of the fifth in living animals 
(rabbits) by introducing a small knife through an opening 
in the parietal bone, along the base of the skull, and cutting 
through the roots near the Gasserian ganglion. The opera- 
tion was followed by complete loss of sensibility upon the 
side on which the nerve had been divided. 8 In this and 
other experiments, however, the animals died a short time 
after the operation. The paper was presented to the Acad- 
emy of Sciences, December 31, 1822, and was published at 
about the same time as the experiments of Mayo. 

In 1824, Magendie published an account of his experi- 
ments on the fifth pair. 3 He divided the nerve at its root, 
by introducing a small stylet through the skull, and noted 
immediate loss of sensibility on the corresponding side of 
the face. Magendie was the first to succeed in keeping the 
animals alive, observing certain interesting remote effects of 
division of the nerve. 

The operative procedure employed by Magendie has 
been followed, with great success, by other physiologists, 
particularly Bernard, to whose researches we are indebted 
for many additional facts of interest concerning the func- 
tions of the fifth nerve. As this is an operation which we 
have frequently performed with success, following the mi- 

1 MAYO, Anatomical and Physiological Commentaries, Number ii., London, 
1823, p. 5. 

2 FODERA, Recherches experimentales sur le systeme nerveux. Journal de physi- 
ologie, Paris, 1823, tome iii., p. 207. 

3 MAGENDIE, De Vinfluence de la cinquieme paire de nerfs sur la nutrition et 
les fonctions de Peril. Journal de physiologic, Paris, 1824, tome iv., p. 176, et 
seq. ; and, Suite des experiences sur les fonctions de la cinquieme paire, Ibid., p. 
302, et seq. 



TKIFACIAL NERVE. 191 

nute directions laid down by Bernard, we will quote from 
him in brief the different steps. 

The nerve may be divided in the cranial cavity with tol- 
erable certainty in rabbits, cats, dogs, and Guinea-pigs, but 
it is most easily done in rabbits. It is difficult, from the 
fact that one is working in the dark, and requires a 
certain amount of dexterity, to be acquired only by 
practice. The instrument used is represented in' 
Fig. 9. It is made by Messrs. Tiemann & Co., of 
Kew York. The operative procedure is as follows : 

1. " The head of the rabbit is firmly held in the 
left hand. The operator feels with the finger of the 
right hand the tubercle situated in front of the ear, 
formed by the condyle of the lower jaw. Behind 
this tubercle, is a hard, osseous portion, the origin of 
the auditory canal. 

2. " The operator penetrates just behind the su- 
perior border of the condyle, directing the point of 
the instrument slightly forward to avoid passing 
into the substance of the petrous portion of the tem- 
poral bone, and thus passes more easily into the 
middle temporal fossa ; at the same time the instru- 
ment is directed a little upward to avoid slipping 
into the zygomatic fossa and thus failing to enter 
the cranial cavity. 

3. "As soon as the instrument has penetrated 
the cranium, which is recognized by the point be- 
coming free, the pressure is arrested and the instru- 
ment is directed downward and backward, its back sliding 
along the anterior face of the bone, which should serve as a 
guide in the operation. 

4. " This point of departure that is to say, the anterior 
face of the bone being found, the instrument is pushed 
along, following its inferior border and proceeding gradu- 
ally, as the instrument penetrates, pressing on the bone, the 
resistance of which can be easily recognized. Soon, how- 

113 



192 NERVOUS SYSTEM. 

ever, the operator feels, at a certain depth, that the bony 
resistance ceases : he is then on the fifth pair, and the cries 
of the animal give evidence that the nerve is pressed 
upon. 

5. l< It is at this moment that it is necessary to hold 
firmly the instrument and the head of the animal ; then the 
cutting edge is turned so as to be directed downward and 
backward, at the same time pressing in this direction so as 
to divide the nerve on the extremity of the petrous portion, 
behind the ganglion of Gasser, if possible, or at least on the 
ganglion itself. 

6. " The instrument is then drawn back, pressing upon 
the bone so as to accomplish completely the section of the 
trunk of the fifth pair ; then it is withdrawn by passing over 
the same course on the anterior face of the petrous portion 
so as not to lacerate the cerebral substance. 

" The accident to be feared in the operation is section of 
the carotid when the instrument has penetrated too far, or 
lesion of the cavernous sinus when it is pressed too far for- 
ward." x 

When this operation has been performed without acci- 
dent, its immediate effects are very striking. The cornea 
and the integument and mucous membrane on that side of 
the head are instantaneously deprived of sensibility, and 
may be pricked, lacerated, or burned without the slightest 
evidence of pain on the part of the animal. Almost always 
the small root of the fifth is divided as well as the large 
root, and the muscles of mastication are paralyzed upon one 
side ; but, with this exception, there is no paralysis of mo- 
tion, sensation alone being destroyed upon one side. 

Immediate Effects of Division of the Trifacial. It is 
hardly necessary to discuss the functions of the trifacial, af- 
ter the statement of the effects which instantly follow upon 

1 BERNARD, Lemons sur la physiologic et la pathologic du systeme nerveux, 
Paris, 1858, .tome ii., p. 53. 



TRJFACIAL NERVE. 193 

its division, taken in connection with its physiological anat- 
omy. The nerve has never been exposed in the cranial 
cavity in living animals ; but its branches upon the face and 
the lingual branch of the inferior maxillary division have 
been operated upon and found to be exquisitely sensitive. 
Longet and others have exposed the roots in animals imme- 
diately after death, and have found that galvanization of the 
large root carefully insulated produces no muscular contrac- 
tion. 1 All who have divided this root in living animals 
must have recognized, not only that it is sensitive, but that 
its sensibility is far more acute than that of any nervous 
trunk in the body. It is much more satisfactory to divide 
the nerve without etherizing the animal, as the evidence of 
pain is an important guide in this delicate operation ; but 
in using anaesthetics, we have never been able to bring an 
animal under their influence so completely as to abolish the 
sensibility of the root itself. For example, in cats that ap- 
pear to be thoroughly etherized, as soon as the instrument 
touches the nerve, there is more or less struggling. The 
large root of the fifth, then, is an exclusively sensory nerve > 
and its sensibility is more acute than that of any other of 
the cerebro-spinal nerves. 

The distribution of the branches of the large root of the 
fifth indicates that it is the great sensitive nerve of the face. 
It will be remembered, however, that its branches go large- 
ly to the organs of special sense, and it is an interesting 
question to determine whether or not these branches be en- 
dowed with special as well as general sensibility. 

Magendie thought, from his experiments upon animals, 
that the fifth nerve was endowed with special sensory prop- 
erties. He states distinctly that section of the nerve is im- 
mediately followed by loss of taste, smell, hearing, and sight, 
on the side operated upon. 8 This view, however, has not 

1 LOXGET, Traite de physiologic, Paris, 1869, tome iii., p. 487. 
- MAGEXDIE, Suite des experiences sur les fondions de la cinquieme paire d 
nerfs. Journal de physiologic, Paris, 1824, tome iv., p. 305, et scg. 

In another volume of the same journal, Magecdie reports a case ha which the 



194: NERVOUS SYSTEM. 

been sustained by more recent experimenters ; and it is 
probable that in some of the experiments of Magendie, other 
nerves were divided as well as the fifth. This is a question 
which will be touched upon again in connection with the 
special senses ; suffice it to say at present that there is 110 
evidence that branches of the fifth pair of nerves are en- 
dowed with olfactory, auditory, or visual sensibility. This 
statement is made without reserve by Miiller, 1 who adduces 
cases of paralysis of the fifth in the human subject in proof 
of its correctness. It is often the case that the special senses 
are affected as an indirect and remote consequence of lesion 
of the fifth, or rather of filaments of the sympathetic con- 
nected with the fifth ; but division of this nerve alone does 
not immediately affect any of the special senses. The loss 
of taste is due always to division of the chorda tympani. 

As far as audition and olfaction are concerned, there are 
no special effects immediately following section of the tri- 
facial ; but there are interesting phenomena observed in 
connection with the eye and the organs of taste. 

At the instant of division of the fifth, by the method just 
described, the eyeball is protruded and the pupil becomes 
strongly contracted. This occurs in rabbits, and the contrac- 
tion of the pupil was observed in the first operations of Ma- 
gendie. 2 The pupil, however, is usually restored to the nor- 
mal condition in a few hours. Longet states that the pupil 
is dilated by division of the fifth in dogs and cats. 3 After 
division of the nerve, the lachrymal secretion becomes very 
much less in quantity ; but this is not the cause of the sub- 
sequent inflammation, for the eyes are not inflamed, as was 
shown by Magendie, even after extirpation of both lachrymal 

sight in one eye was not extinct, the corresponding optic nerve being atrophied, 
but by no means destroyed (La vue peui-elle etre conservee malgre la destruction 
des nerfs optiques, tome viii., p. 27). 

1 MULLER, Physiologic du systeme nerveux, Paris, 1840, tome i., p. 303. 

8 Loc. tit. 

8 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 489, note. 



TRIFACIAL NERVE. 195 

glands. 1 The movements of the eyeball are not affected by 
division of the fifth. 

Another of the immediate effects of complete division of 
the fifth is loss of general sensibility in the tongue. This 
fact was noted by Mayo, in 1S23, 3 and has been confirmed 
by other physiologists. Most experiments upon the influ- 
ence of the fifth over the general sensibility and the sense 
of taste in the tongue have been made by dividing the 
lingual branch of the inferior maxillary division. When 
this branch is irritated, there are evidences of intense pain. 
When it is divided, the general sensibility and the sense of 
taste are destroyed in the anterior third or half of the tongue. 
It will be remembered, however, that the chorda tympani 
joins the lingual branch of the fifth as it passes between the 
pterygoid muscles, and that section of this branch of the fa- 
cial abolishes the sense of taste in the anterior third or half 
of the tongue. 3 If the gustatory properties of the lingual 
branch of the fifth be derived from the chorda tympani, 
lesions of the fifth not involving this nerve would be fol- 
lowed by loss of general sensibility, but the taste would be 
unaffected. This has been shown to be the fact by experi- 
ments upon animals and certain cases of paralysis of general 
sensibility of the tongue without loss of taste in the human 
subject, reported by Schiff * and by Lussana, 6 which will be 
discussed more fully in connection with gustation. 

Among the immediate effects of section of the fifth, is an 
interference with the reflex phenomena of deglutition. In 
some recent researches on the action of the sensitive nerves 

1 MAGEXDIE, De I 'influence de la cinquieme paire des nerfs sur la nutrition et leg 
fonctions de VceiL Journal de physiologie, Paris, 1824, tome iv., p. 179. 

2 MAYO, Anatomical and Physiological Commentaries, Number ii., London, 
1823, p. 10. 

3 See page 155, et seq. 

4 SCHIFF, Lemons sur la physiologic de la digestion, Florence et Turin, 1867, 
tome i., p. 103, et seq. 

6 LUSSAXA, Recherches experimentales et observations pathologiques sur les nerfs 
tugout. Archives de physiologic, Paris, 1869, tome ii,, p. 27, et seq. 



196 NERVOUS SYSTEM. 

in deglutition, by Waller and Prevost, it was found, that after 
section of the fifth upon both sides, it was impossible to ex- 
cite movements of deglutition by stimulating the mucous 
membrane of the velum palati. After section of the superior 
laryngeal branches of the pneumogastrics, no movements 
of deglutition followed stimulation of the mucous membrane 
of the top of the larynx. In these experiments, w r hen the 
fifth was divided on one side, stimulation of the velum upon 
the corresponding side had no effect, while movements of 
deglutition were produced by irritating the velum upon the 
sound side. 1 These experiments show that the fifth nerve 
is important in the reflex phenomena of deglutition, as a 
sensory nerve, ^ conveying the impression from the velum 
palati to the nerve-centres. This action probably takes 
place through filaments which pass from the fifth to the mu- 
cous membrane through Meek el's ganglion. 

Remote Effects of Division of the Trifacial. After the 
ordinary operation of dividing the fifth pair in the cranial 
cavity, the immediate loss of sensibility of the integument 
and mucous membranes of the face and head is usually sup- 
plemented by serious disturbances in the nutrition of the 
eye, the ear, and the mucous membranes of the nose and 
mouth. This curious fact was noted by Magendie, in 1824 ; a 
but it was observed by Mayo, in 1823, in a case of paralysis 
of the fifth in the human subject. 3 At a period varying 
from a few hours to one or two days after the operation, the 
eye upon the affected side becomes the seat of purulent in- 
flammation, the cornea becomes opaque, ulcerates, the hu- 
mors are discharged, and the organ is destroyed. Conges- 
tion of the parts is usually very prominent a few hours after 

1 WALLER ET PREVOST, J&tude relative aux nerfs sensitifs qui president anx phe- 
nomenes reflexes de la deglutition. Archives de physiologie, Paris, 1870, tome iii., 
p. 346, et seq. 

2 Journal de physiologie, Paris, 1824, tome iv., pp. 178, 304. 

3 MAYO, Anatomical and Physiological Commentaries, Number ii., London, 
1823, p. 12. 



TKIFACIAL NEK YE. 197 

division of the nerve. At the same time, there is an in- 
creased discharge from the mucous membranes of the nose 
and mouth upon the affected side, and ulcers appear upon 
the tongue and lips. It is probable, also, that disorders in 
the nutrition of the auditory apparatus follow the opera- 
tion, though these are not so prominent. These phenom- 
ena undoubtedly led Magendie to advance the view that 
section of the fifth involves destruction of the organs of 
special sense, 1 though, as we have seen, these results are con- 
secutive and not immediate. Animals affected in this way 
usually die in from fifteen to twenty days. 

One of the most interesting facts, particularly in view of 
the information derived from later observations, in connec- 
tion with the early experiments of Magendie, is, that he noted 
that " the alterations in nutrition are much less marked " * 
when the division is effected behind the ganglion of Gasser, 
than when it is done in the ordinary way through the gan- 
glion. It is difficult enough to divide the nerve completely 
within the cranium, and is almost impossible to make the 
operation at will through or behind the ganglion, and the 
phenomena of inflammation are absent only in exceptional 
and accidental instances. 'Magendie offers no satisfactory 
explanation of the differences in the consecutive phenomena 
coincident with the locality of section of the nerve. The 
facts, however, have been abundantly verified by Longet, 8 
Bernard, 4 and other experimenters. In the numerous ex- 
periments that we have made upon the fifth pair, we have 
generally noted the consecutive inflammatory phenomena in 
the order above described ; but in exceptional instances, 
these phenomena have been wanting. The following ex- 
periment illustrates these exceptional operations : 

1 Loc. cit. 2 Journal de physiologic, Paris, 1824, tome iv., p. 304. 

3 LONGET, Anatomic et physiologic du systemc ncrreux, Paris, 1842, tome il, 
p. 162. 

4 BERNARD, Lemons sur la physiologic ft la pathologic du systeme nerveux, Paris, 
1858, tome ii., p. 60. 



198 NERVOUS SYSTEM. 

February 6, 1868, the fifth pair of nerves was divided 
upon the left side in a full-grown rabbit in the ordinary way, 
before the class at the Bcllevue Hospital Medical College. 
There followed instant and complete loss of sensibility on 
the left side of the face. Four days after, the animal having 
been fed ad libitum with cabbage, the loss of sensibility was 
still complete. There was very little redness of the conjunc- 
tiva of the left eye, and a very slight streak of opacity, so 
slight that it was distinguished with difficulty. Twelve days 
after the operation, the sensibility of the left eye was dis- 
tinct, but slight. 1 There was 110 redness of the conjunctiva, 
and the opacity of the cornea had disappeared. The animal 
was in good condition, the line of contact of the upper with 
the lower incisors, when the jaws were closed, was very 
oblique. The animal was kept alive by careful feeding with 
bread and milk for one hundred and seven days after the 
operation, there never being any inflammation of the organs 
of special sense. It died at that time of inanition, having 
become very much emaciated. The animal never recovered 
power over the muscles of mastication of the left side, and 
the ineisors grew to a great length, interfering very much 
with mastication, which seemed to be the cause of death. 

Longet, in 1842, furnished a satisfactory explanation of 
the absence of inflammation in certain cases of division of 
the fifth. He attributed the consecutive inflammation in 
most experiments to lesion of the ganglion of Gasser and 
of the sympathetic connections, which are very numerous at 
this point. These sympathetic filaments are avoided when 
the section is made behind the ganglion. 2 

The explanation of the phenomena of disordered nutri- 
tion in the organs of special sense, particularly the eye, fol- 
io wing division of the fifth, is not afforded by the section of 
this nerve alone ; for, as we have seen, when the loss of sen- 

1 We have observed in other experiments gradual return of sensibility, after 
what appeared to have been complete division of the fifth. 

2 LONGET, Anatomic el physiologic du systeme nerveux, Paris, 1842, tome ii., 
p. 162. 



TEEFACIAL NERVE. 199 

eibility is complete after division of the nerve behind the 
Gasserian ganglion, these results may not follow. Xor are 
they explained by deficiency in the lachrymal secretion, for 
they are not observed when both lachrymal glands have 
been extirpated. They are not due to exposure of the eye- 
ball, for they do not follow upon section of the facial. Xor 
are they due simply to an enfeebled general condition, for, 
in the experiment we have detailed, the animal died of inani- 
tion after section of the nerve, without any evidences of in- 
flammation. In view of the fact that section of sympathetic 
filaments is well known to modify the nutrition of parts to 
which they are distributed, producing congestion, increase in 
temperature, and other phenomena, it is rational to infer 
that the modifications in nutrition which follow section of 
the fifth after it receives filaments from the sympathetic sys- 
tem, not occurring when these sympathetic filaments escape 
division, are to be attributed to lesion of the sympathetic, 
and not the division of the sensory nerve itself. 

A farther explanation is demanded for the inflamma- 
tory results which follow division of the sympathetic fila- 
ments joining the fifth, inasmuch as division of the sym- 
pathetic alone in the neck produces simply exaggeration of 
the nutritive processes, as evidenced chiefly by local increase 
in the animal temperature, and not the well-known phenom- 
ena of inflammation. 

It has been remarked by Bernard, that the " alterations 
in nutrition appear more promptly in animals that are enfee- 
bled." ' Section of the small root of the fifth, which is un- 
avoidable when the nerve is divided in the cranial cavity, 
generally interferes so much with mastication as to influence 
seriously the general nutrition ; and this might modify the 

1 BERNARD, Lemons sur la physiologieet la pathologic du systtmc neiveux, Paris, 
1858, tome ii., p. 62. Barnard (op. cit., p. 518), in discussing the effects upon 
calorification and nutrition of the face of division of the sympathetic in the neck, 
states that " the effects of calorification of the great sympathetic may be trans- 
formed into inflammatory phenomena when the animal becomes enfeebled." He 
divided the sympathetic with the pneumogastric in the neck of a dog, on the 



200 NEKVOTJS SYSTEM. 

nutritive processes in delicate organs, like the eye, so as to 
induce those changes which are called inflammatory. The 
following observation, communicated by Dr. "W. H. Mason, 
Professor of Physiology in the Medical Department of the 
University of Buffalo, is very striking in this connection : 

The fifth pair of nerves was divided in a cat in the ordi- 
nary way. By feeding the animal carefully with milk and 
finely-chopped meat, the nutrition was maintained at a high 
standard, and no inflammation of the eye occurred for about 
four weeks. The supply of food was then diminished to 
about the quantity it would be able to take without any spe- 
cial care, when the eye became inflamed, and perforation of 
the cornea and destruction of the organ followed. The ani- 
mal was kept for about five months ; at the end of which 
time, sensation on the affected side, which had been gradu- 
ally improving, was completely restored. 1 

The explanation we have to offer of the consecutive in- 
flammatory effects of section of the fifth with its communicat- 
ing sympathetic filaments is the following : By dividing the 
sympathetic, the eye and the mucous membranes of the nose, 
mouth, and ear are rendered hypersemic, the temperature is 
probably raised, and the processes of nutrition are exagger- 
ated. This condition of the parts would seem to require a 
full supply of nutritive material from the blood, in order to 
maintain the condition of exaggerated nutrition ; but when 
the blood is impoverished, probably as the result of defi- 
ciency in the introduction of nutritive matter, from paraly- 

left side. A few days after, tie made experiments on the salivary secretion, and 
finally took away a portion of the cephalo-rachidian fluid. " This last operation 
made the animal sick and produced an inflammation of the nervous centres : 
death occurred five days after. What was remarkable was that the mucous 
membranes on the side of the face corresponding to the section of the sympa- 
thetic became the seat of violent inflammation, from the moment that the animal 
began to become enfeebled from the disease. There was abundant suppuration 
from the nostril, the buccal mucous membrane, and the conjunctiva of the left 
side, while on the opposite side the corresponding mucous membranes were in 
the normal condition." 

1 Written communication from Prof. Mason. 



TRIFACIAL NERVE. 201 

6is of the muscles of mastication upon one side, the nutri- 
tive processes in these delicate parts are seriously modified, 
so as to constitute inflammation. The observation just de- 
tailed is an argument in favor of this view ; for here the in- 
flammatory action seemed to be arrested when the action of 
the paralyzed muscles was supplied by careful feeding. "With 
this view, the disorders of nutrition observed after division of 
the fifth may properly be referred to the sympathetic system. 

Pathological facts in confirmation of experiments upon 
the fifth pair in the lower animals are not wanting ; but it 
must be remembered that, in cases of paralysis of the nerve 
in the human subject, it is not always possible to locate ex- 
actly the seat of the lesion and to appreciate fully its extent, 
as can be done when the nerve is divided by an operation. 
In studying these cases, it sometimes occurs that the phe- 
nomena, particularly those of modified nutrition, are more 
or less contradictory. 

In nearly all the works on physiology, we find references 
to cases of paralysis of the fifth in the human subject. One 
of the most interesting is the case already referred to, re- 
ported by Mayo, which was published before the experi- 
ments of Magendie. 1 Numerous cases of this kind have 
been collected by Longet.* In the appendix to the work of 
Sir Charles Bell on the Nervous System, several cases are 
reported, 3 observed by himself and collated from various 
sources. We have already referred to the cases cited by 
Schiff and by Lussana, some of which showed alteration of 
taste, while in others this symptom was absent. 4 In a re- 
cent article by Dr. H. D. Noyes, Professor of Ophthalmol- 
ogy in the Bellevue Hospital Medical College, two interest- 

1 See page 196. 

2 LONGET, Anatomic et physiologic du systeme nerveux, Paris, 1842, tome ii., 
p. 191, et seq. 

3 BELL, The Nervous System of the Human Body, London, 1844, Appendix. 

4 See page 195. 

It is unnecessary to cite all the cases reported of paralysis of the fifth, but 
they are quite numerous. In addition to those already referred to, the following 



202 NEEVOUS SYSTEM. 

ing cases are reported, which we had an opportunity of ex- 
amining during the progress of treatment. In both of these 
cases, there was inflammation of the eye. In one case, the 
tongue was entirely insensible upon on side, but there was 
no impairment of the sense of taste. An interesting feature 
in one of the cases was the fact that an operation upon the 
eyelid of the affected side was performed without the slight- 
est evidence of pain on the part of the patient. 1 

These cases of paralysis of the fifth in the human subject 
in the main confirm the results of experiments upon the in- 
ferior animals. In all the cases in w r hich the fifth nerve 
alone was involved in the disease, without the portio dura 
of the seventh, there was simply loss of sensibility upon one 
side, the movements of the superficial muscles of the face be- 
ing unaffected. When the small root was involved, the mus- 
cles of mastication upon one side were paralyzed ; but in cer- 
tain cases in which this root escaped, there was no muscular 
paralysis. The sense of sight, hearing, and smell, except as 
they were affected by consecutive inflammation, were little, 
if at all, disturbed in uncomplicated cases. The sense of 
taste in the anterior portion of the tongue was perfect, except 
in those cases in which the seventh, the chorda tympani, or 
the lingual branch of the fifth after it had been joined by the 
chorda tympani, was involved in the disease. In some cases, 
there was no alteration in the nutrition of the organs of spe- 
cial sense ; but in this respect the facts with regard to the 
seat of the lesion are not so satisfactory as in experiments 
upon the lower animals, it being difficult, in most of them, 
to limit the exact boundaries of the lesion. 

are the most important and satisfactory in their details : The case reported by 
Montault (Journal de physiologic, Paris, 1829, tome ix., p. 113) ; a case by Dr. 
Beveridge (Medical Times and Gazette, London, 1868, No. 921, p. 199); a case 
by Althaus (Medico- Chirurgical Transactions, London, 1869, vol. Hi., p. 27) ; and 
two cases by Rosenthal (Medicinische Jahrbucher, Wien, 1870, Bd. xix., Heft ii. 
und iii., S. 163). 

1 NOTES, Paralysis of the Fifth Cerebral Nerve, and its Effects. New York 
Medical Journal, 1871, vol. xiv., p. 163, et seq. 



CHAPTEK VIII. 



PNEUMOGASTRIC!, OK PAR VAGUM NERVE. 

Pneumogastric nerve (second division of the eighth) Physiological anatomy 
Properties and functions of the pneumogastric General properties of the 
roots Properties and functions of the auricular nerves Properties and 
functions of the pharyngeal nerves Properties and functions of the supe- 
rior laryngeal nerves Properties and functions of the inferior, or recurrent 
laryngeal nerves Properties and functions of the cardiac nerves, and influ- 
ence of the pneumogastrics upon the circulation Depressor-nerve of the 
circulation Properties and functions of the pulmonary branches, and influ- 
ence of the pneumogastrics upon respiration Properties and functions of 
the oesophageal nerves Properties and functions of the abdominal branches 
Influence of the pneumogastrics upon the liver Influence of the pneumo- 
gastrics upon the stomach and intestines Summary of the distribution, 
properties, and functions, of the pneumogastrics. 

OF all the nerves emerging from the cranial cavity, the 
pneumogastric, the second division of the eighth pair, pre- 
sents the greatest number of anastomoses, the most remark- 
able course, and the most varied and interesting functions. 
Arising from the medulla oblongata by a purely sensory 
root, it communicates with at least five motor nerves in its 
course, and is distributed largely to muscular tissue, both of 
the voluntary and the involuntary variety. Finally, there 
is no nerve that has been the subject of such extended and 
elaborate anatomical and physiological investigations, and 
none, concerning the properties and exact functions of which 
there has been so much difference of opinion. 

TTe shall have to treat of the influence of the pneumo- 
gastric upon the act of deglutition, the heart and circulatory 



204: NERVOUS SYSTEM. 

system, the respiratory system, the stomach, intestines, and 
various glandular organs. An indispensable introduction to 
this study is a description of its physiological anatomy. 

Physiological Anatomy. The apparent origin of the 
pneumogastric is from the lateral portion of the medulla 
oblongata, just behind the olivary body, between the roots 
of the glosso-pharyngeal and of the spinal accessory. The 
deep origin '& mainly from what is sometimes called the 
nucleus of the pneumogastric, in the inferior portion of the 
gray substance in the floor of the fourth ventricle. The 
course of the fibres, traced from without inward, is some- 
what intricate. The description of these, given by Yulpian, 
in 1853, has been pretty generally verified by more recent 
dissections, as well as by microscopical investigations. 

Yulpian regards the deep origins of the pneumogastric 
and glosso-pharyngeal nerves as, in the main, identical. 
Tracing the filaments from without inward, he was able to 
follow them in four directions. The anterior filaments pass 
from without inward, first very superficial and directed 
toward the olivary body, but turning before they reach the 
olivary body, they pass deeply into the substance of the res- 
tiform body, in which they are lost. The posterior fila- 
ments are superficial, and pass, with the fibres of the resti- 
form body, toward the cerebellum. Of the intermediate 
filaments, the anterior pass through the restiform body, the 
greatest number extending to the median line in the floor 
of the fourth ventricle. A few fibres are lost in the middle 
fasciculi of the medulla, and a few pass toward the brain. 
The posterior intermediate filaments traverse the restiform 
body to the floor of the fourth ventricle, when some pass to 
the median line, and others descend in the substance of the 
medulla. 1 Yulpian states that he has not been able to fol- 
low the fibres of origin of the pneumogastrics beyond the 

1 VULPIAN, JEssai sur Vorigine de plusieurs paires des nerfs craniens, These, 
Paris, 1853, p. 39. 



PNEUMOGASTEIC KEKVE. 205 

median line, but more recent observations leave no doubt 
of the fact that many of these fibres decussate in the floor 
of the fourth ventricle. 1 

There are two ganglionic enlargements belonging to the 
pneumogastric. In the jugular foramen, is a well-marked, 
grayish, ovoid enlargement, from one-sixth to one-fourth of 
an inch in length, called the jugular ganglion, or the gan- 
glion of the root. This is united by two or three filaments 
with the ganglion of the glosso-pharyngeal. It is a true gan- 
glion, containing nerve-cells. After the nerve has emerged 
from the cranial cavity, it presents on its trunk another 
grayish enlargement, from half an inch to an inch in length, 
called the ganglion of the trunk. This is of rather a plexiform 
structure, the white fibres being mixed with grayish fibres 
and nerve-cells. 

The exit of the nerve from the cranial cavity is by the 
jugular foramen, or posterior foramen lacerum, in company 
with the spinal accessory, the glosso-pharyngeal, and the 
internal jugular vein. 

Anastomoses. The filaments of communication which 
the pneumogastric receives from other nerves are interesting 
from their great importance and their varied sources. The 
most important of these is the branch from the spinal acces- 
sory. There are occasional filaments of communication 
which pass from the spinal accessory to the ganglion of the 
root, but they are not constant. After both nerves have 
emerged from the cranial cavity, an important branch of 
considerable size passes from the spinal accessory to the 
pneumogastric, with which it becomes closely united. Ex- 
periments have shown that these filaments from the spinal 
accessory pass in great part to the larynx by the inferior 
laryngeal nerves. 

In the aquseductus Fallopii, the facial nerve gives off a 

1 DEAN, The Gray Substance of the Medulla Oblongata and Trapezium, Wash- 
ington, 1864, p. 27. 



206 NERVOUS SYSTEM. 

filament of communication to the pneumogastric at the gan- 
glion of the root. This filament, joined at the ganglion by 
sensory filaments from the pneumogastric and some fila- 
ments from the glosso-pharyngeal, is called the auricular 
branch of Arnold. By some anatomists, it is regarded as a 
branch from the facial, 1 and by others it is described with 
the pneumogastric. 8 

Two or three small filaments of communication pass 
from the sublingual to the ganglion of the trunk of the 
pneumogastric.' 

At the ganglion of the trunk, the pneumogastric gener- 
ally receives filaments of communication from the arcade 
formed by the anterior branches of the first two cervical 
nerves. These, however, are not constant. 

The pneumogastric is connected with the sympathetic 
system by numerous delicate filaments of communication re- 
ceived from the superior cervical ganglion, passing in part 
upward toward the ganglion of the root of the pneumogas- 
tric, and in part transversely and downward. These fila- 
ments are frequently short, and, as it were, bind the sympa- 
thetic ganglion to the trunk of the nerve. The main trunk 
of the pneumogastric and its branches receive a few delicate 
filaments of communication from the middle and inferior 
cervical and the upper dorsal ganglia of the sympathetic. 

The pneumogastric frequently sends a very delicate fila- 
ment to the glosso-pharyngeal nerve, at or near the gan- 
glion of Andersch. Branches from the pneumogastric join 
branches from the glosso-pharyngeal, the spinal accessory, 
and the sympathetic, to form the pharyngeal plexus. 

Distribution. In describing the very extensive distribu- 
tion of the pneumogastrics, while the nerves upon the two 
sides do not present any important differences in the desti- 
nation of their filaments as far down as the diaphragm, it 

1 HIRSCHFELD, Systeme nerveux, Paris, 1866, p. 205. 

2 SATPEY, Traite cTanxtomie, Paris, 1852, tome ii., p. 287. 



PXEUMOGASTRIC NERVE. 207 

will be seen that the abdominal branches are not the same. 
The most important branches are the following : 

1. Auricular. 

2. Pharyngeal. 

3. Superior laryngeal. 

4. Inferior, or recurrent laryngeal. 

5. Cardiac, cervical and thoracic. 

6. Pulmonary, anterior and posterior. 

7. (Esophageal. 

8. Abdominal. 

The auricular nerves are sometimes described in connec- 
tion with the facial. They are given off from the ganglion 
of the trunk, and are composed of filaments of communica- 
tion from the facial and from the glosso-pharyngeal, as well 
as of filaments from the pneumogastric itself. The nerve 
thus constituted is distributed to the integument of the up- 
per portion of the external auditory meatus, and a small 
filament, according to Sappey, is sent to the membrana 
tympani. 1 

The pharyngeal nerves are very remarkable in their 
course. They are given off from the superior portion of 
the ganglion of the trunk, and contain a large number of 
the filaments of communication which the pneumogastric 
receives from the spinal accessory. In their course by the 
sides of the superior constrictor muscles of the pharynx, 
these nerves anastomose with numerous filaments from the 
glosso-pharyngeal and the superior cervical ganglion of the 
sympathetic, to form what is known as the pharyngeal 
plexus. The ultimate filaments of distribution pass to the 
muscles and the mucous membrane of the pharynx. Physi- 
ological experiments have shown that the motor influence 
transmitted to the pharyngeal muscles through the pharyn- 
geal branches of the pneumogastric is derived from the spi- 
nal accessory. 2 

The superior laryngeal nerves are given off from the 

1 SAPPEY, Traite cT anatomic, Paris, 1852, tome ii., p. 287. 8 See page 175. 
114 



208 NERVOUS SYSTEM. 

lower part of the ganglion of the trunk. Their filaments 
come from the side opposite to the point of junction of the 
pneumogastric with the communicating branch from the spi- 
nal accessory, so that probably the superior laryngeals con- 
tain few if any motor fibres from this nerve. The superior 
laryngeal gives off the external laryngeal, a long, delicate 
branch, which gives a few filaments to the inferior con- 
strictor of the pharynx, and is distributed to the crico-thy- 
roid muscle and the mucous membrane of the ventricle of 
the larynx. The external laryngeal anastomoses with the 
inferior laryngeal and with the sympathetic. The internal 
branch is distributed to the mucous membrane of the epi- 
glottis, the base of the tongue, the aryteno-epiglottidean fold, 
and the mucous membrane of the larynx as far down as the 
true vocal cords. A branch from this nerve, in its course 
to the larynx, penetrates the arytenoid muscle, to which it 
sends a few filaments, but these are all sensory. This branch 
also supplies the crico-thyroid muscle. It anastomoses with 
the inferior laryngeal nerve. An important branch, de- 
scribed by Cyon and Ludwig, in the rabbit, under the name 
of the depressor-nerve, arises by two roots, one from the su- 
perior laryngeal and another from the trunk of the pneumo 
gastric, passes down the neck by the side of the sympathetic, 
and, in the chest, joins filaments from the thoracic sympa- 
thetic, to penetrate the heart between the aorta and the 
pulmonary artery. 1 This nerve will.be referred to more 
particularly in connection with the influence of the pneu- 
mogastrics upon the circulation. 

It is important, from a physiological point of view, to 
note that the superior laryngeal nerve is the nerve of sensi- 
bility of the upper part of the larynx, as well as the supra- 
laryngeal mucous membranes, and that it animates a single 
muscle of the larynx, the crico-thyroid, and the inferior con- 
strictor of the pharynx. 

1 CYON ET LUDWIG, Action reflexe d?un des nerfs sensibles du, cceur sur les nerfs 
vaso-moteur&, Journal de ranatomie, Paris, 1867, tome iv., p. 472, el seq. 



PXEUMOGASTRIC NERVE. 209 

The inferior, or recurrent laryngeal nerves present some 
slight differences in their anatomy upon the two sides. Upon 
the left side, the nerve is the larger, and is given off at the 
arch of the aorta. Passing beneath this vessel, it ascends 
in the groove between the trachea and the O3sophagus. In 
its upward course, it gives off certain filaments which join 
the cardiac branches, filaments to the muscular tissue and 
mucous membrane of the upper part of the oesophagus, fila- 
ments to the mucous membrane and the inter-cartilaginous 
muscular tissue of the trachea, one or two filaments to the in- 
ferior constrictor of the pharynx, and a branch which joins 
the superior laryngeal. Its terminal branches penetrate the 
larynx behind the posterior articulation of the thyroid with 
the cricoid cartilage, and are distributed to all of the intrin- 
sic muscles of the larynx, except the crico-thyroids, which 
are supplied by the superior laryngeal. 

Upon the right side, the nerve winds from before back- 
ward around the subclavian artery, and has essentially the 
same course and distribution as upon the left side, except 
that it is smaller and its filaments of distribution are not so 
numerous. 

The important physiological point connected with the 
anatomy of the recurrent laryngeals is that they animate all 
of the intrinsic muscles of the larynx, except the crico-thy- 
roid. Experiments have shown that these nerves contain 
numerous filaments from the spinal accessory. 

The cervical cardiac branches, two or three in number, 
arise from the pneumogastrics at different points of the cer- 
vical portion and pass to the cardiac plexus, which is formed 
in great part of filaments from the sympathetic. The tho- 
racic cardiac branches are given off from the pneumogastrics 
below the origin of the inferior laryngeals, and join the car- 
diac plexus. 

The anterior pulmonary branches are few and delicate 
as compared with the posterior branches. They are given 
off below the origin of the thoracic cardiac branches, send 



210 NERVOUS SYSTEM. 

a few filaments to the trachea, then form a plexus which 
surrounds the bronchial tubes and follows the bronchial tree 
to its terminations in the air-cells. The posterior pulmonary 
branches are larger and more numerous than the anterior. 
They communicate freely with sympathetic filaments from 
the upper three or four thoracic ganglia, and then form the 
great posterior pulmonary plexus. From this plexus, a few 
filaments go to the inferior and posterior portion of the tra- 
chea ; a few pass to the muscular tissue and mucous mem- 
brane of the middle portion of the oesophagus ; and a few 
are sent to the posterior and superior portion of the pericar- 
dium. The plexus then surrounds the bronchial tree, and 
passes with its ramifications to the pulmonary tissue, like the 
corresponding filaments of the anterior branches. According 
to Sappey, the pulmonary branches are distributed to the mu- 
cous membrane, and not to the walls of the blood-vessels. 1 

The cesophageal branches take their origin from the 
pneumogastrics above and below the pulmonary branches. 
These branches from the two sides join to form the cesopha- 
geal plexus, their filaments of distribution going to the mus- 
cular tissue and the mucous membrane of the lower third 
of the oesophagus. 

The abdominal branches are quite different in their dis- 
tribution upon the two sides. 

On the left side, the nerve, which is situated anterior to 
the cardiac opening of the stomach, immediately after its 
passage by the side of the oesophagus into the abdomen, di- 
vides into numerous branches, which are distributed to the 
muscular walls and the mucous membrane of the stomach. 
As the branches pass from the lesser curvature, they take a 
downward direction and go to the liver, and, with another 
branch running between the folds of the gastro-hepatic 
omentum, follow the course of the portal vein in the hepatic 
substance. The branches of this nerve anastomose with the 
nerve on the right side and with the sympathetic. 

1 SAPPET, Traite tfanatomie, Paris, 1852, tome ii., p. 294. 



PNEUMOGASTKIC NERVES. 211 

The right pneumogastric, situated posteriorly, at the 
cesophageal opening of the diaphragm, sends a few filaments 
to the muscular coat and the mucous membrane of the 
stomach, passes backward, and is distributed to the liver, 
spleen, kidneys, suprarenal capsules, and finally to the whole 
of the small intestine. 

The branches to the small intestine are very important. 
These were accurately described in 1860, by Kollmann, in 
an elaborate and beautifully-illustrated prize-essay. In the 
plate showing the distribution of this nerve, it is seen that 
the branches to the intestine are very numerous. Accord- 
ing to these researches, the branches described belong to the 
pneumogastric itself, and are not derived from the sympa- 
thetic. 1 When we come to treat of the action of the pneu- 
mogastric upon the small intestine, it will be seen that the 
anatomical researches by Kollmann are fully confirmed by 
physiological experiments. Before the nerves pass to the 
intestines, there is a free anastomosis and interchange of 
filaments between the right and the left pneumogastric. 

Properties and Functions of the Pneumogastric Nerves. 

There is no nerve in the body that has been the subject 
of so many experiments, and concerning which so much has 
been written, as the pneumogastric. Its accessible position 
in many parts of its course, its extensive connections with 
the digestive, the respiratory, and the circulatory system, 
and the evident importance of its relations, have rendered 
the literature connected with its physiology somewhat redun- 
dant. We do not propose to discuss in full all of the views 
entertained from time to time with regard to its functions, 
but to state merely what seem to be well-ascertained facts, 
and the most reasonable inferences, where the facts are diffi- 

1 KOLLMANN, Ueber den Verlauf des Lungenmagennerven in der Bauchhole. 
Mne Prdsschrift. Zeitschrift fur wissenschafiliche Zoologie, Leipzig, 1860, Bd. x., 
S. 413, et seq. 



212 NERVOUS SYSTEM. 

cult of demonstration. In treating cf the functions of this 
nerve, we shall be compelled to make constant reference to 
its anatomy, and for that reason have described pretty fully 
in detail most of the important points in its connections and 
distribution. 

Although the extensive distribution of the pneumogas- 
trics and their importance will necessitate a long discussion 
of their physiology, we shall endeavor to separate the points 
to be considered distinctly, and simplify the subject as much 
as possible. 

We shall first treat of the general properties of those fila- 
ments derived from the true roots of the nerves, and, follow- 
ing them in their course, shall note the properties derived 
from their connections with other nerves. 

We shall then treat of the properties of the different 
branches of the nerves, under distinct heads, taking up these 
branches as they are given off, from above downward. In 
this, we shall consider first the properties and functions 
of the auricular branches ; next, of the pharyngeal branches, 
with their influence upon the action of the pharynx in deglu- 
tition ; next, the superior and inferior laryngeal branches, 
with their relations to the physiology of the larynx ; next 
the cardiac branches, with their influence on the move- 
ments of the heart and the circulation ; next, the pulmonary 
branches, with the function of the nerves in connection with 
respiration ; next, the oesophageal branches, in connection 
with the influence of the nerves upon the action of the 
oesophagus, in deglutition ; next, the abdominal branches, 
with the influence of the nerves in connection with diges- 
tion and the functions of the abdominal viscera. By divid- 
ing up, in this way, the action of the pneumogastrics, it is 
hoped that their physiology may be relieved of much of 
the complexity in which it is apparently involved. 

General Properties of the Hoots of Origin of the Pneu- 
mogastrics. All who have operated on the pneumogastrics 



PXEUMOGASTEIC NERVES. 213 

in the cervical region in living animals have noted their ex- 
ceedingly dull sensibility, as compared with the ordinary 
sensory nerves. Bernard, indeed, states that in this region 
they are generally insensible ; 1 but we have usually found, 
in dogs at least, that their division is attended with slight 
evidences of pain. Without citing in detail all the experi- 
ments on this point, it is sufficient to state that some physi- 
ologists, on galvanizing or otherwise irritating the roots of 
the nerves in animals just killed, have noted movements of 
the muscles of deglutition, of the oesophagus, and the muscu- 
lar coats of the stomach. These experiments have led to the 
opinion that the proper roots of the nerves are motor as well 
as sensory. It becomes, therefore, a difficult as well as an 
important point to determine whether or not the roots be 
of themselves exclusively sensory or mixed. 

In discussing the properties of the roots, we shall rely 
almost entirely upon direct experiments ; though the argu- 
ments drawn from their anatomical characters, in the pres- 
ence of ganglia and the deep origin of their fibres, point 
strongly to their sensory character. 

It is impossible to stimulate the roots, before they haA^e 
received motor filaments from other nerves, in living ani- 
mals, and the experiments are therefore made upon animals 
just killed, before the nervous irritability has disappeared. 
If the true roots of the nerves be exclusively sensory, their 
galvanization in animals just killed should produce, by di- 
rect action, no muscular contraction. If the roots contain 
any motor filaments, contraction of muscles should follow 
their stimulation. The proper physiological conditions in 
such experiments are the following : 

1. It is necessary to stimulate the roots so that the fila- 
ments from the spinal accessory and other motor nerves be 
not involved. 

2. It is important to ascertain, provided movements follow 
such irritation, whether or not they be due to reflex action. 

1 BERNARD, Systeme nerveux, Paris, 1858, tome ii., p. 345. 



214: NERVOUS SYSTEM. 

The first of these conditions is easily fulfilled. All that 
is necessary is to stimulate the roots before the nerves have 
received any anastomosing filaments. To avoid contractions 
of muscles due to reflex action, it is best to divide the roots 
and to stimulate their distal portion. If it be true that 
stimulation of the distal extremities of the roots, the irrita- 
tion so applied as not to involve communicating filaments 
from motor nerves, and not to be conveyed to the centres, 
producing reflex movements through other nerves, does not 
produce any movements, it is fair to assume that the true 
filaments of origin are exclusively sensory. The facts upon 
this point demand careful and critical study ; and it will be 
proper to discard the earlier experiments, made before the 
mechanism of reflex action had been satisfactorily estab- 
lished. 

If the experiments of Longet be accepted without re- 
serve, they prove as conclusively as is possible without ex- 
posing the roots in living animals, an operation which is 
impracticable that the true filaments of origin of the pneu- 
mogastrics are exclusively sensory; at least, that the nerve 
contains no motor filaments except those derived from other 
nerves. The following quotation gives the essential points 
in these experiments : 

" In dogs of large size and in horses, I have isolated in 
the cranium, with the most minute care, the pneumogastric 
of the medulla oblongata and the superior filaments of the 
spinal accessory (internal ~branch\ in order to avoid all reflex 
movement and any derivative current upon the last-named 
nerve ; I then immediately caused the current to act exclu 
sively upon the filaments of origin of the pneumogastric, 
without having ever seen the slightest contraction super- 
vene, either in the muscles of the larynx or pharynx, or in 
the muscular tunic of the oesophagus, or elsewhere. 

" But also I have never failed to demonstrate to all those 
who witnessed my experiments, how it is easy to obtain op- 
posite results in neglecting only one precaution : it suffices, 



PXEUMOGASTRIC XERVES. 215 

for example, to slightly moisten the slip of glass or oiled silk 
which serves to isolate the two nerves, in order that the cur- 
rent should act immediately upon the superior filaments of 
the spinal accessory, from which we have marked contrac- 
tions in the organs just mentioned." 1 

These experiments seem entirely conclusive. In treat- 
ing of the reflex phenomena of deglutition and their rela- 
tions to the superior branches of the pneumogastric, the 
pharyngeal, and the superior laryngeal, it will be seen that 
irritation, either of these nerves or of the mucous membranes 
to which they are distributed, will produce contractions in 
the muscles. All who are practically familiar with the ap- 
plication of electricity to the nerves know how difficult it is 
to insulate the nervous trunks so as to avoid the influence 
of "derived" currents. In carefully studying the experi- 
ments of Longet, it seems that all the physiological condi- 
tions were fulfilled ; and that when the nerve is divided at the 
root and the stimulation is applied to the peripheral end, so 
as to cut oif all reflex action from the nervous centres, and 
when sufficient care is exercised to prevent the propagation 
of the current to the motor connections of the pneumogas- 
tric, the nerve, from its origin at the medulla oblongata to 
the ganglion of the root, contains no motor filaments, and 
is therefore exclusively sensory. 

Among the more recent experiments which have led to 
the view that the roots of the pneumogastrics contain motor 
filaments, are those of Chauveau, made in 1862, and of Yan 
Kempeu, published in 1863. In the experiments of Chau- 
veau, the excitation was applied to the roots of the nerves 
in animals just killed, with the effect of producing energetic 
contractions of the oesophagus and stomach. The roots, 
however, were not divided. 2 It is stated in this article that 
all reflex action ceases in adult mammals with the move- 

1 LOXGET, Trait'e de physiologic, Paris, 1869, tome iii., p. 508. 

2 CHAUVEAU, Du nerf pneumogastrique, etc. Journal de la physiologie, Paris, 
1862, tome v., p. 198. 



2 1C) . NERVOUS SYSTEM. 

ments of the heart. 1 This assumption is too broad ; and 
certainly it would not have been less accurate, and would 
have answered a vital objection, if the nerve had been di- 
vided and galvanization had been applied to its peripheral 
extremity ; for it is well known that so long as the motor 
nerves and the muscles retain their irritability, contractions 
will follow their stimulation after they have been separated 
from the centres. In the experiments just cited, there is 
every reason to believe that the contractions of the oesoph- 
agus and stomach were purely reflex. The remarks just 
made concerning the experiments of Chauveau are equally 
applicable to those of Yan Kempen, in which it is not stated 
that the roots were divided ; 2 and, as far as we know, there 
are no direct observations showing contraction of muscular 
tissue following stimulation of the roots of the pneumogas- 
trics, which cannot be explained by the principle of reflex 
action, or by the supposition that the stimulation was ex- 
tended to communicating motor filaments. In view of these 
facts, we do not consider it necessary to discuss the question 
more fully in detail, and will adopt, without reserve, the 
conclusions of Longet, that the true filaments of origin of 
the pneumogastrics are exclusively sensory, or, at least, that 
they have no motor properties. 

Properties and Functions of the Auricular Nerves. 
There is very little to be said with regard to the auricular 
nerves, after the description we have given of their anat- 
omy. They are sometimes described with the facial and 
sometimes with the pneumogastric. They contain filaments 
from the facial, the pneumogastric, and the glosso-pharyn- 
geal. The sensory filaments of these nerves give sensibility 
to the upper part of the external auditory meatus and the 
membrana tympani. 

1 CHAUVEAU, Du nerf pneumogastrique, etc. Journal ck la physiologic, Paris, 
1862, tome v., p. 193. 

2 VAN KEMPEN, Nouvelles recherche* sur la nature fonct'tonelle des racines du 
nerf pneumogastrique et du nerf spinal. Journal de la physiologic, Paris, 1863, 
tome vi., p. 284, et seq. 



PHAKYXGEAL, XERVES. 217 



Properties and Functions of the Phciryngeal Nemes. 
The pharyngeal branches of the pneumogastric are mixed 
nerves, their motor filaments being derived from the spinal 
accessory. Their direct action upon the muscles of degluti- 
tion belongs to the physiological history of the last-named 
nerve. TTe have already stated, in treating of the spinal ac- 
cessory, that the filaments of communication that go to the 
pharyngeal branches of the pneumogastric are distributed to 
the pharyngeal muscles. 1 

It is impossible to divide all of the pharyngeal filaments 
in living animals and observe directly how far the general 
sensibility of the pharynx and the reflex phenomena of deg- 
lutition are influenced by this section. As far as we can 
judge from the distribution of the filaments to the mucous 
membrane, it would seem that they combine with the pha- 
ryngeal filaments of the fifth, and possibly sensory filaments 
from the glosso-pharyngeal, in giving general sensibility to 
these parts. 

In some recent experiments by Waller and Prevost, on 
the reflex phenomena of deglutition, it is shown that the ac- 
tion of the pharyngeal muscles cannot be excited by stimu- 
lation of the mucous membrane of the supralaryngeal region 
and the pharynx, after section of the fifth and the superior 
laryngeal branch of the pneumogastrics. 3 This would seem 
to show that the pharyngeal branches of the pneumogastrics 
are of little or no importance in these reflex phenomena. 

Properties and Functions of the Superior Laryngeal 
Nei^ues. The distribution of these nerves points to a double 
function ; viz., an action upon the crico-thyroid muscles, and 
the important office of supplying general sensibility to the 
upper part of the larynx and a portion of the surrounding 
mucous membrane. 

1 See page 1 To. 

2 WALLER ET PRETOST, fitude relative crux nerfs semitifs qui president aiiz 
pherwmenes reflexes de la deglutition. Archives de physiologic, Paris, 1870, tome 
UL, p. 347. 



218 NERVOUS SYSTEM. 



The stimulation of these nerves produces intense pain 
and contraction of the crico-thyroids ; but it has been shown 
by experiment that the arytenoid muscles, through which 
the nerves pass, receive no motor filaments. 1 

The action of the nerves upon the muscles is very sim- 
ple, and resolves itself into the function of the crico-thyroids, 
which has been treated of fully under the head of phona- 
tion. 3 When these muscles are paralyzed, the voice be- 
comes hoarse. The filaments to the inferior muscles of the 
pharynx are few and comparatively unimportant. It is im- 
portant in this connection to note that the superior laryn- 
geals do not receive their motor filaments from the spinal 
accessory. 

The sensory filaments of the superior laryngeals have 
Important functions connected with the protection of the 
air-passages from the entrance of foreign matters, particu- 
larly in deglutition, and are further concerned, as we shall 
see, in the reflex action of the constrictors of the pharynx. 
In treating of deglutition, in another volume, we have fully 
discussed the importance of the exquisite sensibility of the 
top of the larynx in the protection of the air-passages. 
When both superior laryngeals have been divided in living 
animals, liquids often pass into the larynx in small quantity, 
owing to the absence of the reflex closure of the glottis 
when foreign matters are brought in contact with its supe- 
rior surface, and the occasional occurrence of inspiration 
during deglutition. 3 

Aside from the protection of the air-passages, the supe- 
rior laryngeal is one of the sensory nerves through which 
the reflex acts in deglutition operate. There are certain parts 
which depend for their sensibility entirely upon this nerve ; 
viz., the mucous membrane of the epiglottis, the aryteno-epi- 
glottidean fold, and the larynx, as far down as the true vocal 
cords. When an impression is made upon these parts, as 

1 LONGET, Traite de physiologic, Paris, 1869, tome Hi., p. 525. 

2 See vol. iii., Voice and Speech, p. 495. z See vol. ii., Digestion, p. 19V. 



SUPERIOR XARYNGEAL SERVES. 219 

when they are touched with a piece of meat, regular and 
natural movements of deglutition ensue. In the recent and 
elaborate experiments of Waller and Prevost, it was shown 
that, after division of the superior laryngeals, excitation of 
the parts supplied with sensory filaments by these nerves 
produced no movements of the pharynx. 1 

The experiments made by galvanizing the trunks of the 
nerves are extremely interesting. If the nerves be divided 
and galvanization be applied to their central ends, move- 
ments of deglutition are observed, and there is also arrest 
of the action of the diaphragm. From these experiments, 
first elaborated by Rosenthal, 3 it would seem that the im- 
pression which gives rise to the movements of deglutition 
aids in protecting the air-passages from the entrance of for- 
eign matters, by temporarily arresting the inspiratory act. 
These experiments of Rosenthal have been repeated very 
extensively by physiologists ; and concerning the effects of 
galvanization of the superior laryngeals upon respiration, 
there is considerable difference of opinion. 

The important point for our consideration, in this con- 
nection, is the action of the nerves in the ordinary phe- 
nomena of deglutition ; and in experiments with galvanism, 
a feeble current simulates most nearly the natural pro- 
cesses. In such experiments, the results have been quite 
satisfactory. Waller and Prevost used a very feeble current, 
and confirmed entirely the observations of Hosenthal. They 
found, also, that galvanization of the roots of the pneumo- 
gastrics above the origin of the laryngeals produced the same 
effects as galvanization of the trunks of the superior laryn- 
geals. 3 The experiments in which a powerful current of 

1 WALLER ET PREYOST, op. cit. Archives de physiologic, Paris, 1870, tome 
iii., p. 347, el seq. 

9 ROSESTHAL, De ^influence du nerf pneumogastrique el du nerf larynge supe- 
rieur sur Ics mouvements du diaphragm. Comptes rendus, Paris, 1861, tome Hi., 
p. 754 ; and, Die Athembewegungen und ihre Beziehungen zum Nerous vagu?, Ber- 
lin, 1862, S. 72. 

8 Loc. cit. 



220 NEKVOUS SYSTEM. 

galvanism was applied to the nerves also show an arrest of 
respiration ; but it is argued that there is nothing special in 
the action of the superior laryngeals under these conditions, 
inasmuch as other sensitive nerves have been found to act 
in the same way. 1 This is undoubtedly true ; but it is well 
known that, in living animals, strong impressions made upon 
any of the acutely sensitive nerves arrest respiration, and 
that this is one of the phenomena commonly observed in 
animals struggling under painful operations. In view of 
these facts, it seems unnecessary to discuss more fully the 
numerous experiments on the effects upon respiration of 
stimulation of the superior laryngeals ; and we can assume 
that it has been demonstrated that an impression made -upon 
the terminal filaments of these nerves, such as occurs in the 
ordinary process of deglutition, excites, by reflex action, con- 
traction of the constrictors of the pharynx, and, at the same 
time, momentarily suspends the movements of the diaphragm. 
Important experiments have been made within the past 
few years, upon the action of the pneumogastrics on the cir- 
culation, in which it is claimed that nervous filaments, arising, 
in the rabbit, in part from the trunk of the pneumogastric 
and in part from the superior laryngeal branch, act as reflex 
depressors of the vascular tension. These experiments will 
be fully discussed in connection with the cardiac branches. 

Properties and Functions of the Inferior, or Recurrent 
Laryngeal Nerves. The anatomical distribution of these 
nerves shows that their most important function is con- 
nected with the muscles of the larynx. The few filaments 
which are given off in the neck to join the cardiac branches 
are probably not very important. It is proper to note, how- 
ever, that it supplies the musculai tissue and mucous mem- 
brane of the upper part of the oesophagus and the trachea, and 
one or two branches are sent to the inferior constrictor of 

1 BERT, Le$ons sur la physiologic comparee de la respiration, Paris, 1870, p. 
459, et seq. 



RECURRENT LARYXGEAL NERVES. 221 

the pharynx. The function of these filaments is sufficiently 
evident. 

The inferior laryngeals contain chiefly motor filaments, 
judging from their distribution as well as from the effects 
of direct irritation. All who have experimented upon these 
nerves have noted little or no evidence of pain when they 
are stimulated or divided. 

One of the most important functions of the recu'rrents is 
connected with the production of vocal sounds. In another 
volume, we have fully treated of th'e mechanism of the voice 
and the action of the intrinsic muscles of the larynx ; 1 and 
in our account of the physiology of the internal, or com- 
municating branch from the spinal accessory to the pneu- 
mogastric, it has been shown that this is the true nerve of 
phonation. 8 In the older works upon physiology, before the 
functions of the spinal accessory were fully understood, the 
experiments on the inferior laryngeals led to the opinion 
that these were the nerves ol phonation, as they showed loss 
of voice following their division in living animals. It is 
true that these nerves contain the filaments which preside 
over the vocal movements of the larynx ; but it is also the 
fact that these vocal filaments are derived exclusively from 
the spinal accessory, and that the recurrents contain as well 
motor filaments which preside over movements of the larynx 
not concerned in the production of vocal sounds. 

The muscles of the larynx concerned in phonation are, 
the crico-thyroids, animated by the superior laryngeals, and 
the arytencid, the lateral crico-arytenoids, and the thyro- 
arytenoids, animated by the inferior laryngeals. The poste- 
rior crico-arytenoids are respiratory muscles ; and it is curi- 
ous that these are not affected by extirpation of the spinal 
accessories, but that the glottis is still capable of dilatation, 
so that inspiration is not -impeded. If, however, the spinal 
accessories be extirpated, and the larynx be then exposed 
in a living animal, the glottis still remains dilated, but will 

1 See vol. ill, Voice and Speech, p. 490, et seq. 8 See page 170, et sey. 



222 NEKVOTTS SYSTEM. 

not close when irritated. If the inferior laryngeals be then 
divided, the glottis is mechanically closed with the inspira- 
tory act, and the animals often die of suffocation. When we 
sCall to mind the varied sources from which the pneumogas- 
trics receive their motor filaments, it is easy to understand 
how certain of these may preside over the vocal movements, 
and others, from a different source, may animate the respira- 
tory movements. 

As we should naturally expect from what has already 
been said, section of the inferior laryngeal nerves paralyzes 
both the vocal and the respiratory movements of the larynx. 
It is not necessary to refer in detail to the ancient and mod- 
ern experiments illustrating this point, the former dating 
from the time of Galen. In adult animals, the cartilages of 
the larynx are sufficiently rigid to allow of inspiration after 
the organ has been completely paralyzed ; but in young ani- 
mals, the glottis is closed, and suffocation ensues. "We have 
generally observed in cats, that suffocation follows immedi- 
ately upon section of the recurrents or of the pneumogastrics 
in the neck. 

The impediment to the entrance of air into the lungs is 
a sufficient explanation of the increase in the number of the 
respiratory acts after division of both recurrents. It has 
been observed by Longet, that the acceleration of respiration 
is much greater in young than in adult animals. This does 
not apply to very young animals, in which section of the re- 
currents produces almost instant death. 1 

Waller and Prevost have shown that feeble galvanization 
of the central ends of the inferior laryngeals, after their di- 
vision, produces rhythmical movements of deglutition, gen- 
erally coincident with arrest of the action of the diaphragm. 
These phenomena are generally observed in rabbits, but 
they are not constant. 3 The reflex action of these nerves in 

1 LONGET, Tralte de physiologic, Paris, 1869, tome iii., p. 533. 

2 WALLER ET PREVOST, Phenomenes reflexes de la deglutition. Archives de 
physiologic, Paris, 1870, tome iii., p. 346. 



CARDIAC NERVES. 223 

deglutition is probably due to the communicating filaments 
which they send to the superior laryngeal nerves. 

Properties and Functions of the Cardiac Nerves, and 
Influence of the Pneumogastrics upon the Circulation. One 
of the most interesting questions connected with the physi- 
ology of the pneumogastric nerves is their action upon the 
heart ; and the results of experiments, which will be fully 
detailed hereafter, are precisely the opposite of what would 
be expected in the case of a nerve containing motor fila- 
ments and distributed to a muscular organ. . Section of the 
pneumogastrics in the neck, far from arresting the action of 
the heart, increases the rapidity of its. pulsations; and gal- 
vanization of the nerves arrests the heart's action in diastole. 

TV"ithin the past few years, some very remarkable experi- 
ments have been made upon the influence of certain nerves 
given off near the superior laryngeals, which have been 
called the depressors of the circulation ; but most observa- 
tions have been made upon the trunks of the pneumogastrics 
in the cervical region, as it is exceedingly difficult to isolate 
the thoracic cardiac branches and to operate upon them with- 
out involving other nervous filaments. In galvanizing the 
nerves in the neck, we have to consider both the direct 
influence of the current and the phenomena due to reflex 
action. 

Effects of Section of the Pneumogastrics upon the Circu- 
lation. It is not necessary to cite in detail the various ex- 
periments upon the effects of section of the pneumogastrics 
in the neck upon the action of the heart. The division of 
these nerves in living animals is sufficiently easy, and all 
who have performed the operation have noted the same re- 
sults. By section of these nerves, the heart is at once sepa- 
rated from one of the most important of its nervous connec- 
tions ; and the effects show that, as far as this organ is con- 
cerned, the motor filaments present great differences from 

115 



NEKVOUS SYSTEM. 



the ordinary motor nerves of the cerebro-spinal system. 
Most of the observations made by dividing the nerves have 
been upon dogs, and the differences in the effects upon other 
animals are slight and unimportant. The following are the 
important phenomena presented in typical experiments : 

Section of one of the pneumogastrics in the neck does 
not produce any very marked effect upon the action of the 
heart, after the slight disturbance which usually follows the 
operation has passed away. The number of pulsations is 
slightly increased, and the cardiac pressure, as shown by a 
cardiometer fixed in the carotid artery, is slightly dimin- 
ished ; but this is insignificant compared with the effects of 
dividing both nerves. 

Section of both pneumogastrics usually produces imme- 
diate and serious disturbance in the respirations, which are 
momentarily accelerated. The animal usually becomes agi- 
tated and suffers from want of air ; and, when it is desired 
especially to note the cardiac disturbance, it is often neceS' 
sary to relieve the respiration by introducing a tube into the 
trachea. In full-grown dogs, however, the respirations soon 
become calm, but are diminished in frequency, and are un- 
usually profound. "When the animal is in this condition, 
the beats of the heart are very much increased in frequency. 
at least doubled ; but they are inefficient and tremulous. 

An interesting point in this connection is the want of in- 
fluence of certain medicinal substances over the action of the 
heart in animals after division of the pneumogastrics. Traube 
has shown that, while digitalis injected into the veins of a 
dog was capable in an hour of reducing the pulse to about 
one-fourth of the normal number of beats per minute, there 
was no appreciable effect upon the circulation when the 
injection was made in animals with both pneumogastrics 
divided. 1 

The influence of the pneumogastrics upon the heart is 

1 TRAUBE, Versuche uber die WirTcung dcr Digitalis. Gesammelte Beitrage zur 
Pathologic und Physiologic, Berlin, 1871, Bd. i., S. 190, et seg. 



CARDIAC NEKVES. 225 

one of the most interesting points in the physiology of the 
circulation ; tut we can discuss the mechanism of the phe- 
nomena following section of the nerves more satisfactorily 
after we have considered the effects of their galvanization. 

Effects of Galvanizing the Pneumogastrics or tJielr 
Branches upon the Circulation. The experiments upon the 
effects of galvanization of the pneumogastrics in the neck 
on the action of the heart are almost innumerable ; and, al- 
though the explanations of the phenomena observed present 
the widest differences, the facts themselves are sufficiently 
simple. These facts will be discussed under the following 
heads : 1. The direct influence of galvanization of the nerves 
in the neck, undivided, or of galvanization of the peripheral 
extremities of the trunks after division. 2. Reflex phenom- 
ena following galvanization of the central ends of branches 
of the pneumogastrics, after their division. 

Direct Influence of the Pneumogastrics on the Heart. 
In 1846, the brothers Weber noted the important fact that 
galvanization of the pneumogastrics in the neck rendered 
the action of the heart slow, and if the galvanization were 
sufficiently powerful, arrested the heart, which remained 
flaccid and in diastole for a certain time while the galvaniza- 
tion was continued. 1 This fact has since been confirmed by 
numerous experimenters, whose observations, however, will 
not be cited in detail, except as they have developed new 
and important phenomena. 

TVhile there is no difference of opinion among physiolo- 
gists with regard to the stoppage of the heart by power- 
ful galvanization, it is stated by some that a very feeble 
current passed through the peripheral ends of the divided 
nerves quickens the heart's action ; but it is admitted by all 
that it is very difficult to regulate the intensity of the cur- 

1 \VEBER, in WAGXER, Handworterbuch der Physiologie, Braunschweig, 1846, 
Bd. iii., Zweite Abtheilung, S. 42, et seq. 



226 NEKVOUS SYSTEM. 

rent so as to produce this effect. After section of the nerves, 
the action of the heart is very readily modified by struggles, 
etc., on the part of the animal under observation ; and, in 
view of the exceeding nicety of the reported experiments, 
it cannot be admitted that the heart is capable of being ex- 
cited to increased rapidity of action, without observations 
of the most positive character. Such facts are wanting; 
and furthermore, it has been shown by Dr. Rutherford, in a 
series of exceedingly exact and satisfactory experiments, that 
whenever a galvanic current passed through the pneumo- 
gastrics has any appreciable effect upon the action of the heart, 
it is to diminish the frequency of its pulsations. 1 Inasmuch 
as our object is simply to show that, imitating the nervous 
force by galvanism, the action of the pneumogastrics is in- 
hibitory, we will not discuss the effects of different currents, 
and other experiments, which have little relation to the 
natural action of the nerves, and possess slight interest from 
a purely physiological point of view. 

The direct action of the pneumogastrics upon the heart 
is undoubtedly through their motor filaments. All the facts 
developed by experiments are in accordance with this view. 
If the nerves be divided in the neck, galvanization of the 
central ends has no effect upon the heart, the pulsations 
being arrested only when the peripheral ends are stimulated. 
This shows that, at least as far as the fibres passing down 
the neck are concerned, the action is centrifugal and di- 
rect, not reflex. Another curious fact illustrates the same 
point very forcibly. It is well known that the woorara- 
poison completely paralyzes the motor nerves, leaving the 
muscular irritability and the sensory nerves intact. It has 
been found that, in animals poisoned with woorara, the action 
}f the heart being maintained by artificial respiration, gal- 
vanization of both pneumogastrics has no effect upon its 

1 RUTHERFORD, Influence of the Vagus upon the Vascular System. Journal 
of Anatomy and Physiology, Cambridge and London, 1869, vol. iii., p. 404, 



CARDIAC NERVES. 227 

pulsations. 1 This fact we have repeatedly verified in public 
demonstrations. 3 Still another curious fact remains bearing 
on the question under consideration. If powerful galvani- 
zation, which immediately arrests the cardiac pulsations, be 
continued for a certain time, so that the motor filaments 
become temporarily exhausted and lose their irritability, the 
heart resumes its contractions, notwithstanding that the 
galvanization is continued ; the nerves being for the time 
incapable of transmitting the inhibitory influence. 3 

The source of the motor filaments in the pneumogastrics 
which exert a direct inhibitory action upon the heart be- 
comes an important point to determine. In the original 
experiments by the brothers Weber, it was shown that, when 
the galvanic stimulus was applied to that portion of the 
centres from which the nerves take their origin, the action 
of the heart was arrested in the same way as when the nerves 
themselves are galvanized ; 4 and it has been shown by sub- 
sequent observations, that when the heart is thus s arrested 
by galvanization of the medulla oblongata, if both pneumo- 
gastrics be divided in the neck, its action is resumed. 5 This 
would at first sight lead to the supposition that the inhibi- 
tory filaments are derived from the roots themselves of the 

1 BERNARD, Lemons sur les effete des substances toxiques et medicamenteuses, 
Paris, 1857, p. 348. 

2 In the inferior classes of animals, there are some exceptional phenomena 
with regard to the pneumogastrics. In experiments made upon alligators, in 
Xew Orleans, in 1861, we found that the action of the heart was promptly ar- 
rested by galvanizing the nerves in the neck, when the animal was killed and 
the general motor nerves were paralyzed by woorara. In some additional ex- 
periments, we showed that all of the nerves were not affected by the poison after 
the same length of time, and that the pneumogastrics were probably the last to 
come under its influence. (See vol. i., Circulation, 1866, p. 234.) Bernard states, 
also, that galvanization of the nerves in birds does not affect the heart, a fact 
for which he offers no explanation. (BERNARD, Systeme nervevx, Paris, 1858, 
tome ii., p. 394.) 

3 LONGET, Traite de physiologic, Paris, 1869, tome ii., p. 117. 

4 WEBER, in WAGNER, Handworterbuch der Physiologic, Braunschweig, 1846, 
Bd. in., Zweite Abtheilung, S. 42. 

5 LONGET, Traite de phy&iologie, Paris, 1869, tome ii., p. 117. 



228 NERVOUS SYSTEM. 

pneumogastrics ; but it has been conclusively demonstrated 
that they -are really derived from the spinal accessories, the 
upper filaments of origin of which are situated just below 
the roots of the pneumogastrics. 

The action of the spinal accessories upon the heart has 
already been considered. 1 The connection between these 
nerves and their influence over the heart may be briefly 
repeated, as follows : 

It has been shown that powerful galvanization of one 
pneumogastric will arrest the heart's action. "Waller, after 
extirpating the spinal accessory nerve upon one side, found 
that galvanization of the pneumogastric upon that side had 
no effect upon the heart, provided that from ten to twelve 
days had elapsed after extirpation of the spinal accessory, 
a sufficient time to secure disorganization and loss of irrita- 
bility of its fibres. These experiments show conclusively 
that the motor filaments contained in the pneumogastric, 
which act directly upon the heart, are derived exclusively 
from the communicating branch of the spinal accessory. 

Reflex Influence, through the Pneumogastrics^ upon tlie 
Circulation. Galvanization of the central ends of the pneu- 
mogastrics, after their division in the neck, does not influ- 
ence the action of the heart, except as the pulsations are 
affected by the modifications in respiration. In experiments 
made upon this point by Bernard, the difference in the ef- 
fects of galvanization of the central and the peripheral ends 
was distinctly noted. When the central ends were stimu- 
lated in dogs, the pupils became dilated, the eyes protruded, 
sometimes vomiting occurred, and always the number of 
respiratory acts was diminished, and, with a powerful cur- 
rent, were arrested in inspiration ; but the pulsations of the 
heart were not affected. 3 

1 See p. 204. 

2 BERNARD, Systems nerveux, Paris, 1858, tome ii., p. 382, et seq. 

The arrest of respiration, particularly the action of the diaphnagm, was first 



DEPRESSOR-NERVE. 229 

Depivssor-Newe. An important reflex action operating 
upon the circulation through branches of the pneumogastrics 
has lately been described by Cyon and Ludwig, in a memoir 
which received the prize for Experimental Physiology from 
the French Academy of Sciences, in 1867. 1 The experi- 
ments on which this memoir is based are exceedingly clear 
and satisfactory, and afford, perhaps, the only positive expla- 
nation we have of reflex action upon the heart. 'The sub- 
stance of these observations is briefly as follows : 2 

In the rabbit is a nerve arising by two roots, one coming 
from the trunk of the pneumogastric and the other from its 
superior laryngeal branch, passing then toward the carotid 
artery and taking its course down the neck by the side of 
the sympathetic as far as the thorax. " In the chest, it joins 
with sympathetic filaments to pass with them to the heart, 
by little branches between the origin of the aorta and the 
pulmonary artery. 

This nerve can be completely isolated in the neck from 
the sympathetic and the trunk of the pneumogastric. If it 
be divided m this situation, after the irritation produced 
by the operation has subsided, very distinct and important 
modifications in the circulation may be produced by its gal- 
vanization. 

In the first place, it was noted in all the experiments, 
that galvanization of the peripheral extremities produced no 
change, either in the number of the pulsations of the heart 
or in the pressure of blood in the vascular system ; which 

noted by Traube. (TRAUBE, Zur Physiologic des Nervus vagus. Gesammdte 
Bdtrdge, Berlin, 1871, Bd. L, S. 184.) 

1 BERNARD, Rapport sur un memoire de M. E. CYOX, intitule : de V action re- 
flexe d>un des nerfs sensibles du cceur. Journal de Tanatomie, Paris, 1868, tome 
v., p. 337. 

2 CYON ET LUDTTIG, Action reflexe d"*un des nerfs sensibles du cceur sur les 
nerfs vaso-moteurs. Journal de V anatomic, Paris, 1867, tome iv., p. 472, et scg. 

Cyon has lately found in the horse, nerves, in their anatomical and physio- 
logical relations, closely resembling the "depressor-nerves" which he first de- 
scribed in the rabbit (British and Foreign Medico- Chirurgical Review, London, 
1871, Xo. xcvi., p. 540). 



230 NERVOUS SYSTEM. 

points to the fact that its action is not direct, but reflex, and 
is due to an impression conveyed to the nerve-centres. 

If the central ends of the nerves be galvanized, the press- 
ure in the arteries diminishes little by little, until it may be 
reduced to one-half or two-thirds of the pressure before the 
irritation was applied. This low pressure continues so long 
as the interrupted current is applied ; but when the galvani- 
zation is arrested, it gradually returns to the normal stand- 
ard. These phenomena are observed in all the large arterial 
trunks. The length of time required to produce the great- 
est diminution in the pressure is somewhat variable, but the 
experimenters have never seen it reach its minimum before 
fifteen pulsations of the heart. 

" The diminution in the pressure is attended with a re- 
duction of the pulse in the instances in which the depressor- 
nerve only has been divided. The irritated nerve is isolated 
in a manner so complete that we cannot fear the passage of 
the exciting current in the trunk of the pneumogastric. The 
changes in the number of pulsations persist even when the 
pneumogastric has been excited by the side where the irri- 
tation has been applied, from the point where the superior 
laryngeal is given off to the point where the pneumogas- 
tric enters the thoracic cavity. 

" From the foregoing it is evident that the changes tak- 
ing place in the number of pulsations are due to excitation 
of the depressor-nerve. If we study attentively the progress 
of the cardiac pulsations during the excitation, we observe 
always that the most considerable reduction takes place at 
the beginning of the experiment ; that is to say, at the 
moment when the blood-pressure descends from its normal 
standard to the lowest point. When the pressure is com- 
pletely depressed, the pulse is accelerated again and even 
reaches almost completely the numbers presented before the 
oscillations. "When the irritation ceases, after a shorter 
or longer period, the heart generally beats more rapidly 
than before the irritation, and this during all the time that 



DEPBESSOK-NERVE. 231 

is occupied in the return of the pressure to the normal stand- 
ard. This observation in itself refutes the idea that the 
diminution in the pressure may depend upon the diminished 
number of pulsations. If the reduction in the rate of the 
pulse produced a diminished pressure, it should be increased 
when the pulsations of the heart become accelerated. 

" The manner in which the pulse is reduced leads to the 
supposition that it is due to a reflex action of the pneunao- 
gastric. 

"It was easy to verify this last opinion, and we have 
been able to confirm it by first cutting the pneumogastrics 
on both sides, and afterward irritating the central end of the 
depressor-nerve. In this case, the pressure fell to 0.62, 0.55, 
etc., while the number of pulsations remained the same, or 
at least oscillated very slightly above and below the number 
observed before the irritation." 

The above extract from the observations of Cyqn shows 
two important points : 

First, galvanic stimulation of the central extremities of 
the divided depressor-nerves reduces the number of pulsa- 
tions of the heart by a reflex action ; the impression being 
conveyed to the nerve-centres by the depressor-nerves, the 
force acting directly upon the heart being transmitted through 
efferent filaments in the trunk of the pneumogastric. 

Second, the reduction in the pressure of blood in the 
larger arteries is independent of the efferent filaments of the 
pneumogastric, and bears no relation to the reduction in the 
number of cardiac pulsations. 

It now remains to explain, if possible, the mechanism of 
the reduction in the arterial pressure. This question is 
treated by Cyon by the method of exclusion. The diminu- 
tion in the pressure followed galvanization of the central ex- 
tremities of the depressor-nerves, even when the heart was 
removed from its influence by section of both pneumogas- 
trics in the neck, and when all the voluntary movements 
and the movements of respiration were abolished by poison- 



232 NERVOUS SYSTEM. 

ing with woorara. In the latter case, the circulation was 
kept up by artificial respiration. 

Without following out the various observations which go 
to show that the influence of the depressor-nerve upon the 
arterial pressure is independent of the force or frequency of 
the heart's action, and is due to some cause which operates 
upon the vessels themselves, we will simply give the results 
of the experiments upon the splanchnic nerves. If the abdo- 
men be opened, and one or more of these nerves be divided, 
the arterial pressure is immediately diminished. After this, 
if the peripheral extremities of the divided nerves be galvan- 
ized, the pressure rapidly returns to the normal standard. 
These experiments " demonstrate that the splanchnic nerves 
constitute the most important vaso-motor nerves in the en- 
tire organism." 

This point being settled, the depressor-nerves were gal- 
vanized after section of the splanchnic nerves, in some cases 
exaggerating the general arterial pressure by compressing 
the aorta, and in others, leaving the aorta free. " The irrita- 
tion of the depressor-nerve after section of the splanchnic 
nerve produced still a diminution in the blood-pressure, but 
the absolute value of this diminution is much less than it was 
during the irritation of the depressor-nerve before the sec 
tion of the splanchnic." 

These experiments show pretty conclusively that the di- 
minished pressure in the arterial system following stimula- 
tion of the central ends of the depressor-nerves after division 
is due to a reflex action on the blood-vessels of the abdomi- 
nal organs, taking place through the splanchnic nerves. We 
are sufficiently familiar with reflex paralyzing action upon 
the blood-vessels through the sympathetic system ; and when 
we call to mind the immense extent of the abdominal vascu- 
lar system, we can readily understand how, if the resistance 
to the flow of blood be diminished by paralysis of the mus- 
cular coats of the small arteries, the pressure in the larger 
arteries would be reduced. 



PULMONARY NERVES. 

^Lechanism of the Influence of the Pneumogastrics upon 
the Action of the Heart. It is useless to speculate upon the 
exact mechanism of the action of the pneumogastrics upon 
the heart. Although various explanations have been pre- 
sented of the effects following division of the nerves in the 
neck, and of the opposite phenomena which attend the gal- 
vanization of their peripheral ends, they are all more or less 
unsatisfactory. All that can be said, in the present state of 
our knowledge, is, that the pneumogastrics have a direct in- 
hibitory influence on the heart. When they are divided, 
and the heart is removed from their influence, the pulsations 
become more rapid. When the peripheral ends of the di- 
vided nerves are galvanized, the heart beats more slowly, or^ 
its action may be arrested by .a current of sufficient power. 
This action may also be reflex, due to an impression con- 
veyed to the centres by what have been described by the 
brothers Cyon and Ludwig, as the depressor-nerves. 



Properties and Functions of the Pulmonary Branches, 
and Influence of the Pneumogastrics iipon Respiration. 
The trachea, bronchi, and the pulmonary structure are 
supplied with motor and sensory filaments by branches of 
the pneumogastrics. The recurrent laryngeals supply the 
upper, and the pulmonary branches, the lower part of the 
trachea, the lungs themselves being supplied by the pulmo- 
nary branches alone. The sensibility of the mucous mem- 
brane of the trachea and bronchi is due to the pneumogas- 
trics, for these parts are insensible to irritation when the 
nerves have been divided in the neck. Longet has shown 
that, while an animal coughed and showed signs of pain 
when the mucous membrane of the respiratory passages was 
irritated, after division of the pneumogastrics there was no 
evidence of sensibility, even when the tracheal mucous mem- 
brane was treated with strong acid, or even cauterized. He 
also saw the muscular fibres of the small bronchial tubes 



23-i NERVOUS SYSTEM. 

contract wlien a galvanic stimulus was applied to the branches 
of the pneumogastrics. 1 

The main interest, in this connection, is attached to the 
pulmonary branches and their relations to the respiratory 
acts. These are undoubtedly connected with important re- 
flex phenomena, acting as centripetal nerves ; and their di- 
rect action in respiration is probably much less important. 
They are exposed and operated upon in living animals with 
so much difficulty, that we know little of the direct effects 
of their irritation, and must judge of their general properties 
chiefly by experiments showing their action upon respira- 
tion. We shall have to study, in connection with the func- 
tions of these nerves, the effects of their division upon the 
lungs and the respiratory acts, and the phenomena, referable 
to the respiratory organs, which follow their galvanization. 
We shall also consider certain theoretical views with regard 
to their action in the automatic processes of respiration, and 
with the sense of want of air (besoin de respirer], which gives 
rise to the reflex respiratory acts. 

Effects of Division of the Pneumogastrics upon Respira- 
tion. Section of both pneumogastrics in the neck, in mam- 
mals and birds, is usually followed by death, in from two to 
five days. In young animals, death may occur almost in- 
stantly, from paralysis of the respiratory movements of the 
glottis, a fact which we have already noted in connection 
with the recurrent laryngeal nerves. 8 In this connection, we 
may note an interesting fact observed by Prof. J. C. Dalton, 
of New York, who has succeeded in keeping dogs alive after 
division of both pneumogastrics in the neck until complete 
recovery took place. In several instances of this kind, after 
killing the animals, Prof. Dalton found complete reunion of 
the divided ends. 8 

Yery little of importance, with regard to the functions of 

1 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 535. 
9 See page 222. 3 Oral communication. 



PULMONARY NEKVES. 235 

the pneumogastrics in connection with respiration, has been 
ascertained by the numerous experiments on record of sec- 
tion of one or both of these nerves in the cervical region. 
It has been found by all experimenters, that animals survived, 
and presented no very distinct abnormal phenomena, after 
section of one nerve. Longet states that animals operated 
upon in this way present hoarseness of the voice and a slight 
increase in the number of respiratory acts. Some observers 
have found the corresponding lung partly emphysematous 
and partly engorged with blood, and others have not noted 
any change in the pulmonary structure. 1 

When both nerves are divided in full-grown dogs, an ex- 
periment which we have often repeated, the effect upon the 
respiratory movements is very marked. For a few seconds, 
the number of respiratory acts may be increased ; but as 
soon as the animal becomes tranquil, the number is very 
much diminished, and the movements change their charac- 
ter. The inspiratory acts become unusually profound, and 
are attended with excessive dilatation of the thorax. The 
animal is generally quiet and indisposed to move. We have 
seen, under these conditions, the number of respirations fall 
from sixteen or eighteen to four per minute. 

In most animals that die from section of both pneumo- 
gastrics, the lungs are found engorged with blood, and, as it 
were, carnified, so that they sink in water. This curious 
fact was noted by Legallois ; 2 and although its physiological 
significance is not apparent, it has been the subject of much 
speculation and experimental research. Many attempts have 
been made to account for this peculiar condition. Traube 
supposed that it was due to the penetration of secretions 
into the respiratory passages ; 3 but this was disproved by 

1 LONGET, Anatomie et physiologic du systeme nerveux, Paris, 1842, tome ii., 
p. 349, et seq. 

MAGEXDIE, Phenomenes physiques de la vie, Paris, 1842, tome i., p. 204. 

2 LEGALLOIS, (Euvres, Paris, 1824, tome i., p. 194. 

3 TRACBE, Die Ursachen und die Bes$haffenheit derjenigen Veranderungen, 



236 NEKVOUS SYSTEM. 

Bernard, who has presented by far the most satisfactory 
explanation of this condition. 

Bernard found that the pulmonary lesion did not exist 
in birds, although section of both nerves was fatal. It had 
previously been ascertained that, in some animals, death 
takes place with no alteration of the lungs. 1 "When the en- 
trance of the secretions into the air-passages was prevented 
by the introduction of a canula into the trachea, the carni- 
fication of the lungs was nevertheless observed. "Without 
detailing all of the experiments upon which the explanation 
offered by Bernard is based, it is sufficient to state that he 
observed a traumatic emphysema as a consequence of the 
excessively labored and profound inspirations. Indeed, this 
can be actually seen when the pleura is exposed in living 
animals. As a result of this distention of the air-cells, the 
pulmonary capillaries are ruptured in different parts, the 
blood becomes coagulated, and the lungs are finally carni- 
fied. This .cannot occur in birds, because the lungs are fixed, 
and their relations are such that they are not exposed to ex- 
cessive distention in inspiration. a 

There is no satisfactoiy explanation of the remarkable 
changes in the respiratory movements that follow section of 
the pneumogastrics. 

Sense of Want of Air. The pneumogastrics may regu- 
late the respiratory acts, but they are not the medium 
through which the sense of want of air (besoin de respirer\ 
which gives rise to the reflex movements of respiration, is 
conveyed to the nerve-centres. If it be true, as it undoubt- 
edly is, that section of both pneumogastrics in the neck 
modifies the number and the character of the respirations, 
and that, after division of the nerves, galvanization of their 
central ends arrests respiration, it is more than probable 

welche das Lungenparenchym nach Durchschneidung der Ner. vagi erleidet. 
Gesammelte Beitrage zur Paihologie und Physiologic, Berlin, 1871, Bd. i., S. 80. 

1 BERNARD, Systeme nerveux, Paris, 1858, tome ii., p. 353. 

8 BERNARD, op. tit., p. 368. 



PULMONARY NEKVES. 237 

that tliis function is normally influenced through these nerves, 
by impressions conveyed to the centres ; but precisely what 
this influence is, or what is the mechanism of its action, we 
do not know. 

The positive statement that the sense of want of air is 
not conveyed to the nerve-centres through the pneumogas- 
trics is based, to a great extent, upon our own experiments, 
which have been fully detailed in another volume,- 1 and we 
will here give simply their results and the conclusions to 
which they lead. 

The acts of respiration are involuntary, though they may 
be modified, within certain limits, through the will ; and 
they are reflex, due to an impression conveyed to the re- 
spiratory nervous centre, the medulla oblongata, which gives 
rise to the stimulus that excites the action of the inspira- 
tory muscles. It has been conclusively shown by experi- 
ments, the first being those of Robert Hook, 3 that if artifi- 
cial respiration be efficiently carried on in a living animal, 
so as to supply air fully to the system, the sense of want of 
air is not appreciated, and the animal makes no effort to 
breathe; but if respiration be imperfectly performed, the 
animal almost immediately feels the want of air, and, in our 
experiments, the exposed respiratory muscles were thrown 
into violent but ineffectual contraction. 

The principal points with reference to the location of the 
sense of want of air and its transmission to the nerve-centres, 
developed by our own experiments, are the following : 

A dog was etherized, the chest was opened, exposing the 
heart and lungs, and artificial respiration was carried on by 
means of a bellows secured in the trachea. So long as the 
supply of air was sufficient, the animal made no effort to 
breathe, even when allowed to come from under the influ- 
ence of the anaesthetic. 

1 See vol. i., Respiration, p. 479, et scq. 

2 An Account of an Experiment made by Mr. Hook, of Preserving Animals 
alive by Blowing through their Lungs vrith BeUows. Philosophical Transactions, 
London, 1667, voL ii., p. 539. 



238 NERVOUS SYSTEM. 

An artery was then exposed and the color of the blood 
noted. "When the artificial respiration was arrested, the 
animal made efforts to breathe as soon as the blood became 
dark in the arterial system. "We concluded from this, that 
the impression conveyed to the respiratory nervous centre, 
giving rise to the movements of respiration, was due to the 
action of the non-oxygenated blood. 

To ascertain whether the impression were made upon 
the nerves distributed to the lungs or upon other nerves, 
a large vessel was divided and the system was drained of 
blood, the lungs being continually supplied with fresh air. 
In this case, respiratory efforts of the most- violent character 
were invariably noted following the haemorrhage. This por- 
tion of the experiment demonstrated that the sense of want 
of air was not dependent upon the accumulation of carbonic 
acid in the lungs, but was due to a deficient supply of the 
oxygen-carrying fluid to the general system. It further 
demonstrated that the impression in the general system was 
not due to the presence of carbonic acid, but to the absence 
of oxygen ; for no blood containing carbonic acid circulated 
in the system. 

These phenomena were observed without any modifica- 
tion, after division of both pneumogastric nerves in the neck, 
and they seem to prove conclusively that the sense of want 
of air is not transmitted to the respiratory nervous centre 
through the medium of these nerves. 1 

Effects of Galvanization of the Pneumogastrics upon 
Respiration. The phenomena which follow galvanization 
of the pneumogastrics, though they are curious and inter- 
esting, do not throw much light upon the relations of these 

1 For a full account of these experiments, with their bearing upon certain 
respiratory phenomena before birth, the reader is referred to the original article, 
entitled, Experimental Researches on Points connected with the Action of the Heart 
and with Respiration, published in the American Journal of the Medical Sciences, 
Philadelphia, October, 1861. Since this publication, the experiments have been 
frequently repeated in public demonstrations, and the conclusions verified. 



PULMONARY SERVES. 239 

nerves to respiration. We have already mentioned the ar- 
rest of the respiratory movements by galvanization of the 
superior laryngeal branches and of the central ends of the 
nerves after their division in the neck. 1 The main point 
of interest in this connection is the fact that the effects 
observed are entirely reflex, galvanization of the peripheral 
ends of the divided nerves having no direct action on the 
movements of the thorax. 

In view of the very indefinite physiological applications 
of the experiments made by galvanizing the nerves, we will 
not give in detail the numerous observations upon this sub- 
ject, but simply state the results, as given in a recent and 
very elaborate work on respiration, by M. Bert : 2 

" 1. Respiration may be arrested by excitation of the 
pneumogastrics (Traube), of the larynx (Cl. Bernard), of 
the nostrils (M. Schiff ), of most of the sensory nerves (M. 
Schiff, an assertion that I have not been able to verify). 

" 2. This arrest may take place eith,er in inspiration or in 
expiration, through any one of these nerves, without attrib- 
uting it to the action of derived currents. 

" 3. A feeble excitation accelerates the respiration ; a 
more powerful excitation retards it ; a very powerful excita- 
tion arrests it. These words feeble ' and i powerful ' hav- 
ing, it is understood, only a relative sense for any one animal 
and under certain conditions : what is feeble for one would 
be powerful for another, etc. 

"I believe, in opposition to the opinion of Eosenthal, 
that section of the pneumogastrics does not increase the 
difficulty of arresting respiration ; at least, death by ex- 
citation occurs much more easily in this case. 

". When the respiratory movements are completely 
arrested, it is always the same for the general movements 
of the animal, which remains motionless. 

1 See page 219. 

9 BERT, Lemons sur la physiologie comparee de la respiration, Paris, 1870, p. 
489, et seq. 

116 



240 NERVOUS SYSTEM. 

" 5. Respiration returns even during excitation, and 
when this is arrested, it almost always becomes accelerated. 

"6. Arrest in expiration is more easily obtained than 
arrest in inspiration ; there are animals, indeed, in which it 
is impossible to effect the latter. 

" 7. If an excitation be employed sufficiently powerful 
to arrest respiration in inspiration, all -respiratory move- 
ments may be made to cease at the very moment when the 
excitation is applied (inspiration, half-inspiration, expira- 
tion), either by operating on the pneumogastric, or oper- 
ating upon the laryngeal. . . . 

"Any feeble excitation of centripetal nerves increases 
the number of the respiratory movements ; any powerful 
excitation diminishes them. A powerful excitation of the 
pneumogastrics, of the superior laryngeal, of the nasal 
branch of the infra-orbital, may arrest them completely ; 
if the excitation be sufficiently energetic, the arrest takes 
place at the very moment it is applied. Finally, sudden 
death of the animal may follow a too powerful impression, 
thus transmitted to the respiratory centre : all this being 
true for certain mammalia, birds, and reptiles." 

The above formulated statements express the experimen- 
tal facts at present known w^ith regard to the influence 
of the pneumogastrics upon respiration. The pulmonary 
branches themselves are so deeply situated that they have 
not as yet been made the subject of direct experiment, with 
any positive and satisfactory results. A theory has recently 
been proposed in which it has been assumed that there are 
two kinds of nerves in the pulmonary branches of the pneu- 
mogastrics, one set being excited by inflation of the lungs, 
which excitation gives rise to expiration, the other set being 
stimulated by collapse of the lungs, which excites inspira- 
tion ; but the experiments upon which this idea is based are 
vague and unsatisfactory. 1 

1 HERING, Die Selbststeu rung der Athmimg durch den Nervus vagus. Sitzungs- 
bericlite der mathematisch-naturuisscnschaftlichen Classe der k. Akademie der Wis* 
mnschaften, Wien, 1868, Bd. Ivii., 2 Abtheilung, S. 672, et seq. 



(ESOPHAGEAL NERVES. 241 

Properties and Functions of the (Esophageal Nemes. 
The muscular walls and the mucous membrane of the oesoph- 
agus are supplied entirely by branches from the pneumogas- 
trics. The upper portion is supplied by filaments from the 
inferior laryngeal branches, the middle portion, by filaments 
from the posterior pulmonary branches, and the inferior 
portion receives the oesophageal branches. These branches 
are both sensory and motor ; but probably the motor fila- 
ments largely predominate, for the mucous membrane, 
though it is sensible to the extremes of heat and cold, the 
feeling of distention, and a burning sensation upon the 
application of strong irritants, is by no means acutely sen- 
sitive. 

That the movements of the oesophagus are animated by 
branches from the pneumogastrics, has been clearly shown 
by experiments. In the first place, except in animals in 
which the anatomical distribution of the nerves is differ- 
ent from the arrangement in the human subject, the entire 
oesophagus is paralyzed by dividing the nerves in the neck. 
In a series of very elaborate experiments, by Chauveau, it 
was shown that section of the nerves in the cervical region 
paralyzed the entire length of the oesophagus in rabbits, but, 
owing to a peculiar distribution of the nerves in dogs, the 
section paralyzed only the terminal portion. 1 

According to Bouchardat and Sandras, 2 Longet, and oth- 
ers, when the pneumogastrics are divided in the cervical 
region, in dogs, if the animals attempt to swallow a consid- 
erable quantity of food, the upper part of the oesophagus is 
found enormously distended. 3 Bernard noted, in a dog in 
which a gastric fistula had been established, that articles of 
food given to the animal did not pass into the stomach, 

1 CHAUVEAF, Du nerf pneumogastrigue considere comme agent excitateur et 
comme aye-it coordinateur dcs contractions cesophagiennes. Journal de la physio- 
logic, Paris, 1862, tome v., p. 342. 

8 BOUCHARDAT ET SAXDRAS, Experiences snr Ics fonctions des nerfs pnewno- 
gaslriques dans la digestion. Comptes rendus, Paris, 1847, tome xxiv., p. 59. 

3 LOXGET, Traite de physiologic, Paris, 1869, tome lit, p. 54T. 



242 NEKVOUS SYSTEM. 

though he made great efforts to swallow. An instant after 
the attempt, the matters were vomited, mixed with mucus, 
but of course did not come from the stomach. 1 

Direct experiments upon the roots of the pneumogastrics 
have shown that these nerves influence the movements of 
the oesophagus, and that their motor filaments are not de- 
rived from the spinal accessory. Chauveau states, as the 
result of numerous observations, that " the oesophagus con- 
tracts throughout its entire length when the roots of the 
pneumogastrics are excited ; it never contracts when the 
bulbar roots of the spinal accessory are excited. 2 

Properties and Functions of the Abdominal Brandies. 
In view of the very extensive distribution of the terminal 
branches of the pneumogastrics to the abdominal organs, it 
is evident that the functions of these nerves must be very 
important, particularly since it has been shown that the 
right nerve is distributed to the whole of the small intes- 
tine. We shall consider the .functions of these branches in 
their relations to the liver, the stomach, and the intestines. 
"We have no positive information with regard to their action 
upon the spleen, kidneys, and suprarenal capsules. 

Influence of the Pneumogastrics upon the Liver. There 
is very little known with regard to the influence of the pneu- 
mogastrics upon the secretion of bile. The only positive 
statements to be found on this subject are those of Longet. 3 
This physiologist has repeatedly remarked, after section of 
the pneumogastrics, that the bile diminishes in density and 
contains less coloring matter than under normal conditions. 
This he attributes to disturbances in the hepatic circulation, 
by which a serous fluid is exuded and mixes with the bile. 

1 BERNARD, Sf/steme nerveux, Paris, 1858, tome ii., p. 422. 
8 CHAUVEAU, Du nerf pneumogaslrique, etc. Journal de la physiologic, Paris, 
1862, tome v., p. 205. 

3 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 552. 



ABDOMINAL NEEVES. 24:3 

The disturbances in the circulation are somewhat similar to 
those occasionally observed in the lungs. The vessels are 
strongly injected, and sometimes contain clots of blood. 
The hepatic tissue is more friable than usual, and presents a 
greenish-black color. 

The most important experiments upon the innervation 
of the liver are those of Bernard, and relate to its glycogenic 
function. TTe shall have little to say on this subject, how- 
ever, in addition to what we have already stated in treating 
of the liver as a sugar-producing organ. 1 The view which 
we have advanced with regard to the glycogenic function is 
that the liver is constantly producing sugar during life, 
which is completely washed out by the blood in its passage 
through this organ, which itself contains little or no sugar, 
under normal conditions. With this view, we are to look 
for sugar in the blood, in certain situations, and not in the 
liver itself; though after death, a change of the glycogenic 
matter in the liver into sugar takes place with great rapidity, 
and sugar may then be found in its tissue, formally, sugar 
disappears in the lungs, and is not found in the blood of the 
arterial system. The presence of sugar in the urine is ab- 
normal. 

Bernard found that if both pneumogastrics be divided in 
the neck, and the animal be killed at a period varying from 
a few hours to one or two days after, the liver contains no 
sugar, under the conditions in which he generally found it ; 
*. ., a certain time after death. From experiments of this 
kind, he concludes that the glycogenic function is suspended 
when the nerves are divided. 2 The experiments, however, 
made by irritating the pneumogastrics, are more satisfactory, 
as in these he looked for sugar in the blood and in the urine, 
and did not confine his examinations to the substance of 
the liver. 

After division of the pneumogastrics in the neck, if the 

1 See vol. iii., Secretion, p. 324, et seq. 

8 BERNARD, Lemons de physiologic experimentale, Paris, 1855, p. 324. 



24:4 NERVOUS SYSTEM. 

peripheral ends be galvanized, there is no effect upon the 
liver ; but if galvanization be applied to the central ends, 
the gljcogenic function becomes exaggerated, and sugar 
makes its appearance in the blood and in the urine. Bernard 
has made a number of experiments illustrating this point, 
upon dogs and rabbits. The galvanic current employed was 
generally feeble, and was continued for from five to ten 
minutes, two or three times in an hour ; in some instances, 
the irritation was kept up for thirty minutes. 1 From these 
experiments, it is assumed that the physiological production 
of sugar by the liver is reflex, and is due to an impression 
conveyed to the nerve-centres through the pneumogastrics. 
A very interesting and adroit experiment by the same ob- 
server shows that section of the pneumogastrics between the 
lungs and the liver does not affect the production of sugar. 
This delicate operation is performed by making a valvular 
opening in the chest, preventing the ingress of air by sud- 
denly forcing the finger into the wound, and then introdu- 
cing a long, delicate hook with a cutting edge, and dividing 
the nerves, which may be reached by the finger in small 
dogs, and feel like tense cords by the side of the oesophagus. 
We have already noted, in another volume, 2 the fact ob- 
served by Bernard and by Pavy, that the inhalation of irri- 
tating vapors and of anaesthetics produces a hypersecretion 
of sugar. 

The remarkable effects of irritating the floor of the fourth 
ventricle, by which we can produce temporary diabetes, have 
been considered fully in connection with the glycogenic 
function of the liver. This effect is not due to a direct trans- 
mission of the irritation to the liver through the pneumo- 
gastrics, for the phenomena of hypersecretion are observed 
in animals upon which this operation has been performed 
after section of both pneumogastrics in the neck. It is prob- 

1 BERNARD, Lemons de physiologic experimentale, Paris, 1855, p. 325 ; and, 
Systeme nerveux, Paris, 1858, p. 437, et seq. 
8 See vol. iii., Secretion, p. 327. 



NERVES. 245 

able, indeed, that the impression is conveyed to the liver 
through the sympathetic system, for it has been shown by 
Schiff and Longet, that animals do not become diabetic after 
irritation of the floor of the fourth ventricle, when the 
branches of the sympathetic going to the solar plexus have 
been divided. 1 The operation, however, of dividing the 
sympathetic nerves in this situation is so serious, that it may 
interfere with the experiment in some other way than by 
the direct influence of the nerves upon the liver. 

Influence of the Pneumogastrics upon the Stomach and 
Intestines. The number of observations that have been 
made upon the influence of the pneumogastric nerves on 
digestion in the stomach is immense, and many of the earlier 
experiments were quite contradictory. We do not propose, 
however, to treat of this subject from a purely historical 
point of view, for the reason that, before 1842 and 1843, 
when gastric fistulas were first established in living animals, 
by Bassow and Blondlot, little was known of the normal 
movements of the stomach and of the mechanism of the 
secretion of the gastric juice ; and farther, before the obser- 
vations of Bouchardat and Sandras, in 1847, the effects of 
section of the nerves in the neck upon the action of the 
oesophagus in deglutition were not understood. If we study 
the literature of the subject anterior to 1842, we find a great 
deal of confusion, due to the facts just stated. Longet, in his 
work on the nervous system, published in 1S42, gives an 
excellent account of the various experiments up to that date. 
He cites a great number of authors, Bichat, Tiedemann and 
Gmelin, Bischoff, Schultz, Breschct and Milne Edwards, 
Magendie, Miiller, Mayo, and many others, to whom we will 
not refer in detail. 2 Leaving out of the question, then, most 
of the earlier experiments, we shall treat of the influence of 

1 LOXGET, Traite de physiologie, Paris, 1869, tome Hi., p. 553. 
* LOXGET, Anatomie et physiologie du systeme nerveux, Paris, 1842, tome iL, 
p. 320, et seq. 



246 NERVOUS SYSTEM. 

the pneumogastrics upon the stomach and intestines, under 
the following heads : 

1. The effects of galvanization of the nerves. 

2. The effects of section of the nerves upon the move- 
ments of the stomach in digestion. 

3. The effects of section of the nerves upon the secre- 
tion of the gastric juice and the chemical processes of di- 
gestion. 

4. The influence of the nerves upon the small intestine. 

Effects of Galvanization. Bichat, in the first edition of 
his great work on general anatomy, published in 1801, states 
distinctly that irritation of the pneumogastrics produces con- 
traction of the muscular coat of the stomach : "I remark 
nevertheless that irritation of one of the vagus nerves, or of 
both, immediately causes the stomach to contract, as occurs 
in a voluntary muscle the nerve of which is irritated. It is 
necessary, in performing this experiment, to open the abdo- 
men of the living animal, and then to irritate the eighth 
pair in the cervical region, in order to have under the eyes 
the organ that is made to contract." 1 This fact was con- 
firmed by Tiedemann and Gmelin, 2 and many others, but 
was denied by M tiller. 3 In more recent experiments, the 
effects of galvanization of the pneumogastrics upon the 
movements of the stomach are unquestionable. Longet 
shows that the stomach contracts as a consequence of irrita- 
tion of the nerves, not instantly, but after the lapse of five 
or six seconds. He explains some of the contradictory re- 
sults obtained by other observers by the fact that these con- 
tractions are very marked during stomach-digestion, while 
they are wanting " when the stomach is entirely empty, 

1 BICHAT, Anatomic generale, appligitee d la physiologic et d la pathologic, 
Paris, 1801, seconde partie, tome iii., p. 360. 

2 TIEDEMANN ET GMELIN, Recherches experimentalcs, physiologiques et chimiques, 
Mir la digestion, Paris, 1827, premiere partie, p. 374. 

8 MULLER, Elements of Physiology, London, 1840, vol. i., p. 530. 



ABDOMINAL NEEVE3. 24:7 

retracted on itself and in a measure in repose." According 
to the same author, irritation of the splanchnic nerves, while 
it produces movements of the intestines, does not affect the 
stomach. Judging from the tardy contraction of the stom- 
ach and the analogy between the action of the pneumo- 
gastrics upon this organ and the action of the sympathetic 
nerves upon the non-striated muscular tissue, Longet assumes 
that the motor action of the pneumogastrics is due, hot to the 
proper filaments of these nerves, but to filaments derived from 
the sympathetic system. " This interpretation removes the 
singular physiological anomaly that an organ, the action 
of which is entirely removed from the control of the will, 
should depend upon a voluntary, or cerebro-spinal nerve." l 
This explanation of the contradictory results of experiments 
and of the mechanism of the action of the pneumogastrics 
upon the stomach seems entirely satisfactory, and may be 
accepted without reserve. 

Effects of Section of the Pneumogastrics upon the Move- 
ments of the Stomach. If the pneumogastrics be divided in 
the neck in a dog in full digestion, in which a gastric fistula 
has been established so that the interior of the organ can be 
explored, the following phenomena are observed : 

In the first place, before division of the nerves, the mu- 
cous membrane of the stomach is turgid, its reaction is in- 
tensely acid, and, if the finger be introduced through the 
fistula, it will be firmly grasped by the contractions of the 
muscular walls. When the pneumogastrics are divided, un- 
der these conditions, the contractions of the muscular walls 
instantly cease, the mucous membrane becomes pale, the 
secretion of gastric juice is apparently arrested, and the sen- 
sibility of the organ is abolished. 3 Paralysis of the stomach, 
etc., had been noted, 3 long before the observations of Ber- 

1 LOXGET, Traiti de physiologic, Paris, 1869, tome iii., p. 546. 

2 BERNARD, Systems nerveux, Paris, 1858, tome ii., p. 422.. 

3 TIEDEMANN- ET GMELix, JKeckerches sur la digestion, Paris, 1827, premiere 
partie, p. 373. 



248 NERVOUS SYSTEM. 

nard ; but his experiments on animals with a fistulous open- 
ing into the stomach are the most striking. 

Notwithstanding the apparent arrest of the movements 
of the stomach in digestion by section of the pneumogastrics, 
experiments carefully performed show that substances may 
be very slowly passed to the pylorus, and that the move- 
ments, though they are immensely diminished in activity, 
are not entirely abolished. This fact has been established 
beyond question by the experiments of Schiff, who attributes 
the movements occurring after section of the nerves to local 
irritation of the intramuscular terminal nervous filaments. 1 

Effects of Section of the Pneumogastrics upon Digestion, 
etc. Since the publication of the second volume of this work, 
in which we considered briefly the action of the pneumogas- 
trics in digestion, we have reviewed the literature of the sub- 
ject, as well as the publications that have appeared since 
that time, but we find little, if any thing, to add to the state- 
ments already made. 2 The facts with regard to the effects 
of division of the nerves in the cervical region upon the se- 
cretion of gastric juice are briefly as follows : 

"When both nerves are divided, while an animal is in full 
digestion, the mucous membrane becomes pale and flaccid, 
and the secretion of gastric juice is apparently arrested at 
once ; but if the animal survive the operation for a day or 
two, a small quantity of juice may be secreted as the result 
of local stimulation, and digestion of a very small quantity 
of food, finely divided and introduced into the stomach 
by a fistulous opening, may take place. 3 A serious difficulty 
in the digestion of large masses of food after division of the 
nerves is due to the cessation of the movements of the 
stomach. It is stated by Tiedemann and Gmelin, that di- 

1 SCHIFF, Lemons sur la physiologic de la digestion, Florence et Turin, 1867, 
tome ii., p. 389. 

8 See vol. ii., Digestion, p. 283. 

3 LONGET, Traite de physiologic, Paris, 18691, tome in., p. 649. 



ABDOMINAL NERVES. 249 

gestion may be to a certain extent reestablished, under these 
conditions, by galvanizing the peripheral extremities of the 
divided nerves. 1 

There is very little to be said with regard to the relations 
of the pneumogastrics to the sensations of hunger and thirst. 
It would be very natural to infer, from the distribution of 
these nerves to the mucous membrane of the stomach, that 
they should be involved in these sensations ; but in treating 
of this subject elaborately, in connection with alimentation, 
we have shown that hunger and thirst really have their ori- 
gin in the general system, though the sensations are referred 
subjectively to the stomach and fauces, and that, in all prob- 
ability, the sensations persist after division of both pneumo- 
gastrics. 2 

"With regard to the influence of the pneumogastrics upon 
absorption from the stomach, we have also mentioned the 
fact, demonstrated by Longet, that the passage of poisons 
from the stomach into the blood-vessels may be retarded by 
section of the nerves, but is not prevented. 3 

Physiologists have given but little attention to the influ- 
ence of the pneumogastrics upon the intestinal canal, for the 
reason that the distribution of the abdominal branches to 
the small intestine, notwithstanding the researches of Koll- 
mann, in 1860, does not appear to be generally recognized. 
The right, or posterior abdominal branch was formerly sup- 
posed to be lost in the sernilunar ganglion and the solar 
plexus, after sending a few filaments to the stomach ; but since 
it has been shown that this nerve is supplied to the whole of 
the small intestine, 4 its physiology, in connection with intes- 
tinal secretion, has assumed considerable importance. 

In an admirable series of experiments, by Prof. 'Horatio 
C. Wood, Jr., of Philadelphia, the importance of the abdomi- 



1 TIEDEMAXN ET GMELiy, RecJierches sur la digestion, Paris, 1827, premiere 
partie, p. 373. 

8 See vol. ii., Alimentation, p. 14. 

4 See p. 211. 



250 NEKVOTJS SYSTEM. 

nal brandies of the right nerve is fully illustrated. 1 These 
experiments show, in the most conclusive and satisfactory 
manner, that the pneumogastrics influence intestinal as well 
as gastric secretion. One of the most interesting and curi- 
ous points in connection with their function is, that after 
section of the nerves in the cervical region, the most power- 
ful cathartics, croton-oil, calomel, podophyllin, jalap, arsenic, 
etc., fail to produce purgation, even in doses sufficient to 
cause death. The articles used were either given by the 
mouth, just before dividing the nerves, or were injected un- 
der the skin. 

Though the observations of Dr. "Wood are not entirely 
new, they are by far the most extended and satisfactory, and 
were made with a knowledge of the fact of the distribution of 
the nerves to the small intestine. Dr. Wood quotes freely from 
the experiments made by Sir Benjamin Brodie 2 and by Dr. 
John Reid. 3 Brodie failed to produce purging in dogs when 
both pneumogastrics had been divided in the neck after the 
administration of arsenic by the mouth and injecting it un- 
der the skin. Dr. Reid made five experiments, and in all 
but one, it is stated that diarrhoea existed after division of 
the nerves. In twenty experiments by Dr. "Wood, there 
was no purgation after division of the nerves, in one there 
was free purgation, and in one there was " some slight muco- 
fecal discharge." From these, Dr. Wood concludes, that 
while section of the cervical pneumogastrics, in the great 
majority- of instances, arrests gastro-intestinal secretion and 
prevents the action of purgatives upon the intestinal canal, 

1 WOOD, On the Influence of Section of the Cervical Pneumogastrics upon the 
Action of JZmetics and Cathartics. American Journal of the Medical Sciences, 
Philadelphia, 1870, New Series, vol. lx., p. 75, et seg. 

2 BRODIE, Experiments and Observations on the Influence of the Nerves of the 
Eiglitli Pair on the Secretions of the Stomach. Philosophical Transactions, Lon- 
don, 1814, vol. xiv., p. 104. 

3 REID, Experimental Investigation into the Functions of the Eighth Pair of 
Nerves. Physiological, Anatomical, and Pathological Researches, London, 1848, 
p. 245, et seq. 



SUMMARY OF THE PNEUMOGASTRICS. 251 

a few exceptional cases occur in which these effects are not 
observed. 

The facts just mentioned are exceedingly interesting in 
connection with the experiments of Traube upon the action 
of digitalis after section of the pneumogastrics. It will be 
remembered that, in these experiments, digitalis failed to 
diminish the number of beats of the heart when the nerves 
had been divided in the neck, showing that the separation 
of the heart from its connections with the cerebro-spinal 
system removed the organ from the peculiar and character- 
istic effects of the poison. 1 

It would be interesting to determine whether the pneu- 
mogastrics influence the intestinal secretions through their 
own fibres or through filaments received from the sympa- 
thetic system; but there are no experimental facts suffi- 
ciently definite to admit of a positive answer to this question. 
If the action take place through the sympathetic system, as 
in the case of the stomach, the filaments of communication 
join the pneumogastrics high up in the neck, and become 
incorporated with the true fibres of the nerve in its trunk. 

Summary of the Distribution, Properties, and Functions 
of the Pneumogastrics. The pneumogastrics have their ap- 
parent origin from the lateral portion of the medulla oblon- 
gata, just behind the olivary bodies, between the roots of 
the glosso-pharyngeals and the spinal accessories. Their 
deep origin is mainly from the gray substance in the floor 
of the fourth ventricle. In their course, they each present 
two ganglia, the ganglion of the root and the ganglion of the 
trunk. They pass out of the cranial cavity on either side, by 
the posterior foramen lacerum, with the glosso-pharyngeals, 
the spinal accessories, and the internal jugular veins. 

The nerves receive anastomosing branches from the spinal 
accessories, facials, sublinguals, the anterior roots of the up- 
per two cervicals, and the sympathetic. The nerves fre- 

1 See p. 224. 



252 NERVOUS SYSTEM. 

quently send branches to the glosso-pharyngeals ; and fila- 
ments joining others from the glosso-pharyngeals, the spinal 
accessories, and the sympathetic, go to form the pharyngeal 
plexus. 

From above downward, the branches of the pneumogas- 
trics are the following : 

1. The auricular, distributed to the integument of the 
upper portion of the external auditory meatus and to the 
membrana tympani. 

2. The pharyngeal, containing motor filaments derived 
from the spinal accessory, distributed to the muscles and 
mucous membrane of the pharynx. 

3. The superior laryngeals, distributed to the mucous 
membrane of the epiglottis, base of the tongue, aryteno- 
epiglottidean folds, ventricles of the larynx and lining mem- 
brane as far as the true vocal cords, and to the crico-thyroid 
muscle. From these nerves and the main trunk of the 
pneumogastrics, arise the so-called depressor-nerves of the 
circulation. 

4. The inferior laryngeals, turning around the great ves- 
sels at the top of the thorax, pass up the neck, sending 
filaments to the upper part of the oesophagus, trachea, and 
the inferior constrictors of the pharynx, their terminal 
branches supplying all of the muscles of the larynx except 
the crico-thyroids. 

5. The cervical and thoracic cardiac branches, going to 
the cardiac plexus, to be distributed to the heart. 

6. The anterior and posterior pulmonary branches, dis- 
tributed to the pulmonary tissue, following out the bronchial 
tree to its minutest ramifications, and sending a few fila- 
ments to the trachea and to the pericardium. 

7. The cesophageal branches, distributed to the lower 
third of the oesophagus. 

8. The abdominal branches, the left distributed to the 
stomach and the liver ; and the right, sending a few fila- 
ments to the stomach, and distributed finally to the liver, 



SUMMARY OF THE PNEUMOGASTRICS. 253 

spleen, kidneys, suprarenal capsules, and the whole of the 
small intestine. 

The true filaments of origin of the pneumogastrics are 
exclusively sensory, and the nerves contain no motor fila- 
ments, except, those derived from their anastomoses. 

The sensory filaments of the auricular branches give sen- 
sibility to the upper part of the external auditory meatus 
and the membrana tympani. 

The motor filaments of the pharyngeal branches animate 
the muscles of the pharynx. The sensory filaments are not 
important in the reflex phenomena of deglutition, but prob- 
ably contribute slightly to the general sensibility of the 
pharynx. 

The superior laryngeal nerves give sensibility to the up- 
per portion of the larynx. They are exquisitely sensitive, 
and, by their reflex action, aid in closing the larynx to the 
entrance of foreign substances, and in the production of the 
movements of deglutition. Stimulation of these nerves pro- 
duces movements of deglutition and arrests the action of the 
diaphragm. They animate, also, the movements of the crico- 
thyroid muscles. 

The inferior laryngeals contain chiefly motor filaments. 
They embrace the filaments from the spinal accessories, which 
preside over phonation. They also contain motor filaments 
from other sources, which preside over the respiratory move- 
ments of the glottis. Their division abolishes vocal sounds, 
and, in young animals, causes death by suffocation, the glot- 
tis being closed in inspiration. Galvanization of their cen- 
tral ends, after division, generally produces movements of 
deglutition and arrest of the action of the diaphragm. 

The action of the cardiac branches has been studied by 
experiments upon the pneumogastrics in the cervical region. 
Division of the pneumogastrics in the neck increases the 
number of pulsations of the heart. Galvanization of the 
peripheral ends, after division, arrests the heart's action in 
diastole, and galvanization of the central ends has no effect 



254: NERVOUS SYSTEM. 

on tlie circulation. The direct inhibitory action of the pneu- 
mogastrics operates through filaments derived from the spinal 
accessories. Galvanization of the " depressor-nerves " retards, 
or may arrest the pulsations of the heart, by reflex action. 
This occurs only when the central ends of the divided nerves 
are stimulated. Galvanization of the central ends of these 
nerves also diminishes the pressure of blood in the large ves- 
sels. This is due to reflex action through the splanchnic 
nerves, by which the vessels of the intestines are dilated. 
No such effect is produced when the splanchnic nerves have 
been divided. There is no entirely satisfactory explanation 
of the influence of the pneumogastrics on the heart. 

The action of the pulmonary branches has been studied 
chiefly by observations on the pneumogastrics in the cervical 
region. Division of the pneumogastrics in this situation, in 
young animals, produces almost instant death by closure of 
the glottis in inspiration. In animals full-grown, death oc- 
curs in from two to five days, and the respiratory acts are 
very much diminished in frequency. "When death occurs in 
this way, the lungs are found partially or completely " car 
nified." This is due to mechanical causes. The small pul- 
monary vessels are ruptured by the excessively deep inspira- 
tions, and blood is gradually effused and coagulates. The 
pneumogastrics have but little to do in conveying to the 
nerve-centres the sense of want of air which gives rise to 
the respiratory movements. Galvanization of the central 
ends of the pneumogastrics divided in the cervical region 
has the following effects : A very feeble excitation accele- 
rates, and a more powerful excitation retards respiration. 
A sufficiently powerful excitation arrests respiration. Gal- 
vanization of the peripheral ends has no effect on respira 
tion. 

The cesophageal branches supply only the lower third of 
the oesophagus. The upper portion receives branches from 
the inferior laryngeals, and the middle portion is supplied 
by branches from the posterior pulmonary nerves. The sen- 



SUMMARY. OF THE PlfEUMOGASTEICS. 255 

sibility of tlie mucous membrane of the oesophagus, as well 
as the movements of its muscular coat, depends upon these 
branches. Division of the nerves paralyzes the oesophagus, 
and galvanization of the roots of the pneumogastrics causes 
the tube to contract in its entire length. When the nerves 
are divided, the oesophagus may become distended with food 
forced in by the constrictors of the pharynx, but little or 
none passes to the stomach. Uegurgitation of food some- 
times occurs under these conditions, the muscular coat of 
the oesophagus contracting under the direct stimulus of dis- 
tention. 

The function of the abdominal branches has been studied 
chiefly by operating on the pneumogastrics in the cervical 
region. Division of the nerves produces congestion of the 
liver, and sometimes slight extravasation, and renders the 
bile somewhat watery. It also arrests, in from one to two 
days, the glycogenic function of the liver. Galvanization 
of the peripheral ends of the divided nerves has no effect 
on the liver. Galvanization of the central ends exaggerates 
the glycogenic function and renders animals diabetic. The 
inhalation of irritating vapors or of anaesthetics has the same 
effect. This action is reflex, and the direct stimulus to the 
liver does not pass through the pneumogastrics, for division 
of the nerves between the lungs and the liver has no influ- 
ence on the production of sugar. Irritation of the floor of 
the fourth ventricle, opposite the origin of the pneumogas- 
trics, exaggerates the glycogenic function. The stimulus is 
not propagated through the pneumogastrics, for the effect is 
the same after both nerves have been divided. It probably 
operates through the sympathetic,, for diabetes cannot be 
produced after the branches going to the solar plexus have 
been divided. 

Section of the pneumogastrics in the neck paralyzes, 

nearly but not entirely, the muscular coats of the stomach. 

AYhen the section is made in an animal in full digestion, the 

mucous membrane, from being tense and full of blood, be 

117 



256 NERVOUS SYSTEM. 

comes pale and flaccid, and stomach-digestion is arrested. 
Afterward, very feeble movements of the stomach may oc- 
cur as the result of local irritation, and small quantities of 
food, very finely divided, may be digested. Galvanization 
of the nerves in the neck produces contractions of the mus- 
cular coats of the stomach. This action probably takes place 
through sympathetic filaments going to the pneumogastrics 
high up in the cervical region. Section of the nerves slight- 
ly retards absorption from the stomach. 

After division of both pneumogastrics in the neck, purga- 
tive poisons, given even in fatal doses, generally fail to pro- 
duce watery discharges from the intestine. 1 

1 Compression of the pneumogastrics has lately been recommended by Wal- 
ler to produce anaesthesia in surgical operations, etc. The effects of pressure 
of these nerves in the human subject are described by Aristotle, quoted by 
Waller. In some cases, the patient falls instantly, as if struck by lightning, 
while in others the effects are not so marked. Waller has employed this method 
for the production of anaesthesia under varied conditions, and has never ob- 
served any serious after-effects. He relates a case of successful reduction of a 
very difficult dislocation of the shoulder, which had resisted previous efforts, 
after two or three minutes of simultaneous compression and traction. He also 
relates a case of painless extraction of a tooth by the same means. The im- 
possibility of compressing the pneumogastrics, in the human subject, without 
disturbing the circulation in the brain by pressure on the carotids, in view of 
the fact that cerebral anaemia produces anaesthesia, renders it impossible to ac- 
cept, without reserve, the conclusions of Waller. (WALLER, On the Compression 
of the Vagus Nerve, considered as a Means of producing Asthenia or Ancesthesia 
in Surgical Operations, Practitioner, London, December, 1870, No. xxx., p. 
822.) 



CHAPTER IX. 

PHYSIOLOGICAL ANATOMY AND GENERAL PROPERTIES OF THE 
SPINAL CORD. 

General arrangement of the cerebro-spinal axis Membranes of the encephalon 
and spinal cord Cephalo-raehidian fluid Physiological anatomy of the 
spinal cord Direction of the fibres after they have penetrated the cord by 
the roots of the spinal nerves General properties of the spinal cord 
Effects of stimulation applied directly to different portions of the cord. 

UNDER the head of special senses, we shall consider, in 
another volume, the properties and functions of the first and 
second nerves, the portio mollis of the seventh, or auditory, 
and the gustatory nerves, comprising a part of the glosso- 
pharyngeal and a small filament from the facial (the chorda 
tympani) going to the lingual branch of the fifth. This will 
include a full account of the organs of smell, sight, hearing, 
and taste, with a description of the general sensory nerves, 
as far as they are concerned in the sense of touch. "We will 
here begin our history of the cerebro-spinal axis, which will 
include the physiological anatomy, properties, and functions 
of the encephalon and spinal cord. 

General Arrangement of the Cerebro-spinal Axis. The 
nervous matter contained in the cavity of the cranium and 
in the spinal canal, exclusive of the roots of the cranial and 
spinal nerves, is known as the cerebro-spinal axis. This 
portion of the nervous system is composed of white and 
gray nervous matter. The fibres of the white matter act as 
conductors. The gray matter constitutes a chain of ganglia, 



258 - NERVOUS SYSTEM. 

whicli act as nerve-centres, receiving impressions and gen- 
erating the so-called nerve-force. The gray matter of the 
spinal cord also serves, to a greater or less extent, as a con- 
ductor. 

The cerebro-spinal axis is enveloped in membranes, for 
its protection and for the support of its nutrient vessels. It 
is surrounded, to a certain extent, with liquid, and presents 
cavities, as the ventricles of the brain and the central canal 
of the cord, which contain liquid. The gray matter is dis- 
tinct from the white, even to the naked eye. In the spinal 
cord, the white substance is external and the gray is internal. 
The surface of the brain presents an external layer of gray 
matter, the white substance being internal. In the white 
substance of the brain, also, we find collections of gray 
matter. As we should expect from the similarity in func- 
tion between the white matter and the nerves, this por- 
tion of the cerebro-spinal axis is composed largely of fibres. 
The gray substance is composed chiefly of cells. 

The encephalon is contained in the cranial cavity. In 
the human subject and in many of the higher animals, its 
surface is marked by numerous convolutions, by which the 
extent of its gray substance is very much increased. The 
cerebrum, the cerebellum, and all of the encephalic ganglia 
are connected with the white substance, and are contin- 
uous with the spinal cord. With the encephalon and the 
cord, all of the cerebro-spinal nerves are connected. The 
cerebro-spinal axis acts as a conductor, and its different col- 
lections of gray matter, or ganglia receive impressions con- 
veyed by the sensory conducting fibres, and generate nerve- 
force, which is transmitted to the proper organs by the motor 
fibres. 

Membranes of the Encephalon and Spinal Cord. The 
membranes of the brain and spinal cord are, the dura mater, 
the arachnoid, and the pia mater. 

The dura mater of the encephalon is a dense, fibrous 



CEKKBRO-SPESTAL AXIS. 259 

membrane, in two layers, composed chiefly of inelastic tis- 
sue, which, lines the cranial cavity and is adherent to the 
bones. In certain situations, its two layers become sepa- 
rated and form what are known as the venous sinuses. The 
dura mater also sends off folds or processes of its internal 
layer ; one of these passes into the longitudinal fissure, and 
is called the falx cerebri ; another lies between the cerebrum 
and the cerebellum, and is called the tentorium; another 
is situated between the lateral halves of the cerebellum, and 
is called the falx cerebelli. The dura mater is closely at- 
tached to the bone at the border of the foramen magnum, 
From this point, it passes into the spinal canal and forms a 
loose covering for the cord. In the spinal canal, this mem- 
brane is not adherent to the bones, which have, like most 
other bones in the body, a special periosteum. At the fora- 
mina of exit of the cranial and the spinal nerves, the dura 
mater sends out processes which envelop the nerves, with 
the fibrous sheaths of which they soon become continuous. 

The arachnoid is an excessively delicate serous membrane, 
in two layers, the surfaces of which are nearly in contact. The 
external layer lines the internal surface of the dura mater. 1 
Like the other serous membranes, the arachnoid is covered 
with a layer of tessellated epithelium. There is a small 
amount of liquid between the two layers of the arachnoid ; 
but by far the greatest quantity of liquid surrounding the cere- 
bro-spinal axis lies beneath both layers, in what is called the 
subarachnoid space. This is called the cerebro-spinal, or 
cephalo-rachidian fluid. The fact that it exists in greatest 
quantity beneath both layers of the arachnoid was first 
pointed out by Magendie. 3 The arachnoid does not follow 
the convolutions and fissures of encephalon or the sulci of 

1 According to Kolliker, the arachnoid consists of a single layer, the layer 
attached to the dura mater being not properly a membrane, but simply an 
epithelial covering (Handbuch der Gewebelehre, Leipzig, 1867, S. 308). 

2 HAGEXDIE, JRecherches physiologiques et cliniques sur le liquide cephalo- 
rachidien, Paris, 1842. 



260 NERVOUS SYSTEM. 

the cord, but simply covers their surfaces. Magendie point- 
ed out a longitudinal, incomplete, cribriform, fibrous septum 
in the cord, passing from the inner layer of the arachnoid to 
the pia mater. A similar arrangement is found in certain 
situations at the base of the skull. 1 

The pia mater of the encephalon is a delicate fibrous 
structure, exceedingly vascular, seeming to present, indeed, 
only a skeleton net-work of fibres for the support of the ves- 
sels going to the nervous substance. This membrane cov- 
ers the surface of the encephalon immediately, follows the 
sulci and fissures, and is prolonged into the ventricles, where 
it forms the choroid plexus and the velum interpositum. From 
its internal surface, small vessels are given off which pass 
into the nervous substance. 

The pia mater of the encephalon is continuous with the 
corresponding membrane of the cord ; but in the spinal 
canal, it is thicker, stronger, more closely adherent to the 
subjacent parts, and its blood-vessels are by no means so 
numerous. In this situation, many of the fibres are arranged 
in longitudinal bands. This membrane lines the anterior 
sulcus and a portion of the posterior sulcus. It is sometimes 
spoken of as the neurilemma of the cord. 

At the foramina of exit of the cranial and the spinal 
nerves, the fibrous structure of the pia mater becomes con 
tinuous with the nerve-sheaths. 

Between the anterior and posterior roots of the spinal 
nerves on either side of the cord, is a narrow ligamentous 
band, the ligamentum denticulatum, which assists in holding 
the cord in place. This extends from the foramen magnum 
to the terminal filament of the cord, and is attached, inter- 
nally, to the pia mater, and externally, to the dura mater. 

It is not necessary to enter into a detailed description of 
the arrangement of the blood-vessels, nerves, and lymphatics 
of the membranes of the brain and spinal cord, or of the vas- 
cular arrangement in the substance of the cerebro-spinal axis, 

1 MAGENDIE, op. cit., p. 14. 



CEPHALOKACHIDIAN FLUID. 261 

as these points are chiefly of anatomical interest. The circu- 
lation in these parts presents certain peculiarities. In the 
first place, the encephalon being contained in an air-tight 
case of invariable capacity, it has been a question whether 
or not the vessels be capable of contraction and dilatation, 
or whether the quantity of blood in the brain be subject to 
modification in health or disease. This question may cer- 
tainly be answered in the affirmative. In infancy and in the 
adult, when an opening has been made in the skull, the volume 
of the encephalon is evidently increased during expiration and 
is diminished in inspiration. Under normal conditions, in the 
adult, it is probable that the amount of blood is increased in 
expiration and diminished in inspiration ; but it is not prob- 
able that the cerebro-spinal axis undergoes any considera- 
ble movements. The important peculiarities in the cerebral 
circulation have already been folly considered in another 
volume. 1 

An important fact was pointed out by Hobin, and after- 
ward by His, with regard to the arrangement of the lym- 
phatic vessels of the brain. It was shown by these observers, 
that the encephalic capillaries are surrounded or nearly sur- 
rounded by canals (perivascular canal-system) which exceed 
the blood-vessels in diameter by from y^Vo to T J- - of an 
inch, and are connected with lymphatic trunks or reservoirs 
situated under the pia mater. 8 The system of canals may, 
by variations in its contents, serve to equalize the amount 
of liquid in the brain as its blood-vessels are distended or 
contracted. 

Cephalo-rachidian Fluid. The older writers referred 
to in works upon physiology, as giving the most accurate 
description of the cephalo-rachidian fluid, are Haller 3 and 
Cotugno; 4 but it remained for Magendie, in 1825, to de- 

1 See vol. i., Circulation, p. 332. * See vol. ii., Absorption, p. 433. 

3 HALLER, Elemento Physiologies, Lausannae, 1762, tomus iv., p. 87. 

4 Extraii de la dissertation de COTUGXO, de Ischiade Nervosa, content dans le 



262 NERVOUS SYSTEM. 

scribe its exact situation, with the communications between 
the different cavities of the brain and the subaraclmoid 
space. 1 By a series of ingeniously-contrived experiments 
upon the cadaver and in living animals, Magendie showed 
that the greater part of the fluid in the cranium and the 
spinal canal is contained in what is known as the sub- 
arachnoid space; that is, between the inner layer of the 
arachnoid and the pia mater, and not between the two lay- 
ers of the arachnoid. The ventricles of the encephalon are 
in communication with the central canal of the cord, and, as 
was shown by Magendie, they are also in communication 
with the general subaraclmoid space, by a narrow, triangu- 
lar orifice, situated at the inferior angle of the fourth ventri- 
cle. By this arrangement, the liquid in the ventricles of the 
encephalon and the central canal of the cord communicates 
with the liquid surrounding the cerebro-spinal axis, and the 
pressure upon these delicate parts is equalized. 

As far as we know, the function of the cephalo-rachidian 
fluid is simply mechanical, and its properties and composi- 
tion have no very definite physiological significance. Its 
quantity was estimated by Magendie at about two fluid- 
ounces ; a but this was the smallest amount obtained by 
placing the subject upright, making an opening in the lum- 
bar region and a counter-opening in the head to admit the 
pressure of the atmosphere. The exact quantity in the liv- 
ing subject could hardly be estimated in this way ; and it is 
difficult, indeed, to see how any thing more than a roughly 
approximative idea could be obtained. The quantity ob- 
tained by Magendie probably does not represent the entire 
amount of liquid contained in the ventricles and in the sub- 

TJicmurus Dissertationum de SANDIFERT, tome ii., p. 411, Koterdara, 1769. 
Journal de physiologic, Paris, 1827, tome vii., p. 83. 

1 MAGENDIE, Memoire sur un liquids qui se trouve dans le crane et le canal 
vertebral de Vhomme et des animaux mammiferes. Journal de physiolcgie, Paris, 
1825, tome v., p. 27; Ibid., 1827, tome vii., pp. 1, 66; and, Recherches phy'siolo- 
giques el d'miques sur le liquide cephalo-rachidien, Paris, 1842. 

2 MAGENDIE, Liquide cephalo-rachidien, Paris, 1842, p. 36. 



CEPHALCKRACHIDIAN FLUID. 263 

araclmoid space, but it is the most definite estimate that has 
been given. 

The discharge of a certain quantity of the cephalo-rachid- 
ian fluid does not produce any marked derangement in the 
action of the nervous system. In the first experiments of 
Magendie, in which the muscles of the neck and the occipito- 
atloid ligament were divided, the animals were affected with 
irregular movements, general paralysis, etc. ; * but it is stated 
by Longet 2 and by Bernard, that these phenomena are due 
to the division of the parts involved in the operation, and 
not to the removal of the liquid. When the liquid is al- 
lowed to flow spontaneously through a small trocar intro- 
duced without division of the muscles of the neck, there fol- 
lows no serious nervous disturbance ; but when the liquid is 
drawn out forcibly with a syringe, the animal first becomes 
enfeebled, and afterward seems affected with general paraly- 
sis. These phenomena are attributed by Bernard, not so 
much to removal of the fluid, as to congestion of blood-ves- 
sels and even effusion of blood, which follow sudden dimi- 
nution in the pressure. 3 

Sudden increase in the quantity of liquid surrounding 
the cerebro-spinal axis produces coma, probably from com- 
pression of the centres. This was shown by Magendie, by 
injecting water in animals, and also by compressing the tu- 
mor, in cases of spina bifida in the human subject, by which 
the fluid was pressed back into the spinal canal. In the 
cases of spina bifida, the subject, during the compression, 
fell into coma, which was instantly relieved by removing 
the pressure. 4 

It was ascertained by Magendie, and this has been con- 
firmed by all later observers, that the cephalo-rachidian fluid 

1 MAGENDIE, Liquide cephalo-rachidien, Paris, 1842, p. 58. 

2 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 305. 

3 BERNARD, Sy&teme nerveux, Paris, 1858, tome i., p. 496, et seq. 

Bernard states that Magendie recognized the error in his first interpretation of 
the phenomena following removal of the cephalo-mchidian fluid (Ibid., p. 496). 

4 MAGENDIE, op. cit., p. 60. 



264 NEKVOTTS SYSTEM. 

is speedily reproduced after its evacuation. In all probabil- 
ity, it is secreted by the pia mater. 1 

The general properties and composition of the fluid un- 
der consideration are, in brief, the following : 2 It is perfectly 
transparent and colorless, free from viscidity, of a distinctly 
saline taste, alkaline reaction, and resists putrefaction for 
a long time. It is not affected by heat or acids. As we 
should expect from its low specific gravity and purely me- 
chanical function, it contains a large proportion of water ; 
981 to 985 parts per thousand. It contains a considerable 
quantity of chloride of sodium, a trace of chloride of potas- 
sium, sulphates, carbonates, and alkaline and earthy phos- 
phates. In addition, it contains traces of urea, glucose, lac- 
tate of soda, fatty matter, cholesterine, and albumen. 

As a summary of the function of the cephalo-rachidian 
fluid, it may be stated, in general terms, that it serves to 
protect the cerebro-spinal axis, chiefly by equalization of the 
pressure in the varying condition of the blood-vessels, accu- 
rately filling the space between the centres arid the bony 
cavities in which they are contained. That the blood-vessels 
of the cerebro-spinal axis are subject to variations in tension, 
is readily shown by introducing a canula into the subarach- 
noid space, when the jet of fluid discharged will be increased 
with every violent muscular effort. 3 The pressure of the 
fluid, in this instance, could only be affected through the 
blood-vessels. 

Physiological Anatomy of the Spinal Cord. 

The spinal cord, with its membranes, the roots of the 
spinal nerves, and the surrounding liquid, occupies the spinal 
canal and is continuous with the encephalon. Its length is 
from fifteen to eighteen inches, and its weight is about an 
ounce and a half. Its form is cylindrical, slightly flat- 

1 Op. cit, pp. 38, 39. 

2 ROBIN, Le$ons sur las humeurs, Paris, 1867, p. 259. 

3 MAQENDIE, Journal de physiologic, Paris, 1827, tome vii., p. 9. 



ANATOMY OF THE SPINAL COED. 265 

tened in certain portions. It extends from the foramen 
magnum to the first lumbar vertebra. It presents, at the 
origin of the brachial nerves, an elongated enlargement, and 
a corresponding enlargement at the origin of the nerves 
which supply the lower extremities. It terminates below in 
a slender, gray filament, called the filum terminale. The 
sacral and coccygeal nerves, after their origin from the lower 
portion of the cord, pass downward to emerge by the sacral 
foramina, and form what is known as the cauda equina. 

The substance of the cord is formed of white and gray 
matter, the white matter being external. The proportion 
of white matter to the gray is greatest in the cervical region. 
This fact is important in studying the course of the fibres 
and in view of the functions of the cord as a conductor. 
The inferior, pointed termination of the cord consists en- 
tirely of gray matter. 

The cord is marked by .an anterior and a posterior me- 
dian fissure, and by imperfect and somewhat indistinct an- 
terior and posterior lateral grooves, from which arise the 
anterior and the posterior roots of the spinal nerves. The 
posterior lateral groove is tolerably well marked, but there 
is no distinct line at the origin of the anterior roots. The 
anterior median fissure, or sulcus, is perfectly distinct. It 
penetrates the anterior portion of the cord in the median 
line for about one-third of its thickness, and receives a high- 
ly-vascular fold of the pia mater. It extends to the anterior 
white commissure. The posterior fissure is not so distinct 
as the anterior, and is not lined throughout by a fold of the 
pia mater, but is filled with connective tissue and blood-ves- 
sels, which form a septum posteriorly, between the lateral 
halves of the cord. The posterior median fissure, so called, 
extends nearly to the centre of the cord, to the posterior 
gray commissure. 

Physiologically and anatomically, the cord is divided 
into two lateral halves ; but the division of each half into 
columns is not so distinct. Anatomists generally regard a 



NERVOUS SYSTEM. 

half of the cord as consisting of three columns : The ante- 
rior column is bounded by the anterior fissure and the ori- 
gin of the anterior roots of the spinal nerves ; the lateral 
column is included between the anterior and the posterior 
roots of the nei'A^es ; the posterior column is bounded by the 
line of origin of the posterior roots and the posterior fis- 
sure. Some anatomists include the lateral with the anterior 
column, under the name of the antero-lateral column, taking 
in about two-thirds of the cord. Next the posterior median 
fissure, is a narrow band, marked by a faint line, which is 
sometimes called the posterior median column. 

The arrangement of the white and the gray matter in 
the cord is seen in a transverse section. The gray substance 
is in the form of a letter H, presenting two anterior and two 
posterior cornua connected by whatsis called the gray com- 
missure. The anterior cornua are the shorter and broader, 
and do not reach to the surface of the cord. The posterior 
cornua are larger and narrow, and extend nearly to the sur- 
face, at the point of origin of the posterior roots of the spi- 
nal nerves. In the centre of the gray commissure, is a very 
narrow canal, lined by cells of ciliated epithelium, called the 
central canal. This is in communication above with the 
fourth ventricle, and extends below to the filum terminale. 
That portion of the gray commissure in front of this canal 
is sometimes called the anterior gray commissure, the poste- 
rior portion being known as the posterior gray commissure. 
The central canal is immediately surrounded by connective 
tissue. In front of the gray commissure, is a mass of white 
substance known as the anterior white commissure. 

The proportion of the white to the gray substance is 
variable in different portions of the cord. In the cervical 
region, the white substance is most abundant, and, in fact, 
it progressively increases in quantity from below upward 
throughout the whole extent of the cord. In the dorsal 
region, the gray matter is least abundant, and it exists in 
greatest quantity in the lumbar enlargement. 



ANATOMY OF THE SPINAL COED. 267 

The white substance of the cord is composed of nerve- 
fibres, connective-tissue elements, and blood-vessels, the lat- 
ter arranged in a very wide and delicate plexus. The nerve- 
fibres are variable in their size, and are composed of the 
axis -cylinder surrounded by the medullary substance, with- 
out, however, the investing membrane. AYe will speak far- 
ther on of the direction of the fibres in the cord. 

The anterior cornua of gray matter contain blood-vessels, 
connective-tissue elements, very fine nerve-fibres, and large 
multipolar nerve-cells, which are sometimes called motor 
cells. The posterior cornua are composed of the same ele- 
ments, the cells being much smaller, and the fibres exceed- 
ingly small, presenting very fine plexuses. The cells in this 
situation are sometimes called sensory cells. I^ear the pos- 
terior portion of each posterior cornu, is an enlargement, of 
a gelatiniform appearance, containing numerous small cells 
and fibres, called the substantia gelatinosa. 

The foregoing description of the different structures and 
parts of the cord is necessary to a comprehension of the di- 
rection of the fibres in the spinal axis and their connections 
with the nerve-cells, which is the anatomical basis of our 
knowledge of its physiology. The connections between the 
cells and the fibres have already been described in the chap- 
ter on the general structure of the nervous system. 1 The 
multipolar nerve-cells are supposed to present certain pro- 
longations which do not branch and are directly connected 
with the medullated nerve-fibres. These are called nerve- 
prolongations. In addition, fine, branching poles are de- 
scribed under the name of protoplasmic prolongations. 

The direction of the fibres in the cord is one of the most 
difiicult and complicated questions in physiological anatomy ; 
and, especially as regards the posterior roots of the nerves, 
is one which cannot as yet be elucidated by purely anatomi- 
cal investigations, but requires the aid of experimental and 
pathological observations. 

1 See page &0. 



NEKVOUS SYSTEM. 

Direction of the Fibres after they have penetrated itie 
Cord l)y ih^e Roots of the Spinal Nerves. In order to under- 
stand fully the importance of this question, it is necessary to 
bear in mind the following physiological facts : 

1. The cord serves as a conductor of impressions to the 
brain, conveyed to it through the posterior roots, and of 
stimulus generated by the brain and passing from the cord 
by the anterior roots of the spinal nerves. This action is 
crossed, the decussation taking place mainly at the medulla 
oblongata, for the anterior portions, and throughout the 
whole extent of the cord, for the posterior portions. 

2. Independently of its action as a conductor, the cord, 
disconnected from the rest of the cerebro-spinal axis, acts as 
a nerve-centre, by virtue of its gray matter and the fibres 
connected with the cellular elements of this substance. 

Bearing in mind these points, which are matters of posi- 
tive demonstration, we are prepared to study the anatomical 
relations of the fibres and cells. In this, we cannot follow 
minutely and critically discuss the elaborate investigations 
of Stilling, Clarke, Kolliker, Yan der Kolk, Gerlach, Dean, 
and others, without treating extensively of points which pos- 
sess a purely anatomical and a more or less controversial in- 
terest ; and we will content ourselves with the following very 
recent description, quoted in full from Gerlach, which em- 
bodies about all of our positive knowledge of the subject, 
presented in the clearest manner possible. This extract, the 
translation of which is almost literal, should be carefully 
studied by those who desire to learn what is known at the 
present day with regard to the physiological anatomy of the 
cord. As a preparation for this study, it would be well to 
closely examine Fig. 10, which gives a general view of the 
different parts of the cord, shown in a transverse section : 

" With the present methods and means of investigation 
at our command, we can scarcely give an exact, detailed de- 
scription of the course of the fibres in the spinal cord, the 
ground-work of the physiology of this organ. Investigations 



AXATOMY OF THE SPIXAL COKD. 



269 



up to this time afford at least the outlines of a sketch which, 
as regards the course of the fasciculi of the anterior roots, 
has a tolerably definite basis ; and, on the other hand, with 



FIG. 10. 




Transverse section of the spinal cord of a child six months old, at the middle of the lumbar en- 
largement treated with potassio-chloride of gold and nitrate of uranium i>y means of these 
.ts. the direction of the fibres in the gray substance is rendered unusually distinct. 
Magnified 20 diameters. a, anterior columns; 6. posterior columns: c. lateral columns; 
d, anterior roots ; e, posterior roots ; f, anterior white commissure, in communication with 
the fasciculi of the anterior cornua and the anterior columns ; g, central canal with its epithe- 
lium; //, surrounding connective substance of the central canal; i. transverse fasciculi of the 
gray commissure in front of the central canal; l\ transverse fasciculi of the gray commissure 
behind the central canal ; , transverse section of the two central veins ; m. anterior cornua ; 
11. great lateral cellular layer of the anterior cornna ; o. lesser anterior cellular layer; p. small- 
est, median cellular layer"; g. posterior cornua ; r, ascending fasciculi in the posterior cornua ; 
*. substantia gelatinosa (GERLACIL in STEICKEB, Ilandbudi der Lehre von, den Geweben, 
Leipzig, 1868, S. 666). 

regard to the fasciculi going to the spinal cord through the 
posterior roots, is quite incomplete and uncertain. 

" The fasciculi of the anterior roots, after their entrance 
into the cord, pass diagonally through the white substance, 



270 NEKVOUS SYSTEM. 

and, as such, are not at all concerned in its formation. On 
the contrary, they pass immediately to the gray substance 
of the anterior cornua, and, by their prolongations, are in 
direct connection with the nerve-cells in this situation, which, 
accordingly, are to be regarded as the elements of origin of 
the anterior roots in the cord. The protoplasmic processes 
of these nerve-cells form parts of the fine plexuses of nerve- 
fibres in the gray substance, from which larger nerve-fibres 
take their origin. These, extending in two directions, leave 
the gray substance, to pass up in the white substance to the 
brain. In consequence of the entrance of additional nerve- 
fibres, the white substance is necessarily increased in quan- 
tity in the cord from below upward. "With regard to the 
course of the fasciculi which pass out of the gray substance 
of the anterior cornua, these are to be divided into median 
and lateral. The median fasciculi pass immediately into the 
anterior white commissure, where they decussate w r ith corre- 
sponding fasciculi from the opposite side, to pass upward 
again in the anterior column of the other half of the cord. 
The lateral fasciculi go to the lateral columns of the same side, 
in which they pass to the brain, having first undergone de- 
cussation in the anterior pyramids of the medulla oblongata. 
" The posterior nerve-roots enter horizontally, running 
in the white substance of the spinal cord, in a direction from 
without inward toward the median line, and here divide into 
two portions. The lateral portion, the smaller, retains the 
horizontal direction, and passes through the substantia gelati- 
nosa, dividing into fine and the finest bundles, in the man- 
ner mentioned above, to take part in the formation of the 
vertical bundle of fibres which lie immediately in front. 
Here the fibres pass onward, a portion of them ascending 
and a portion descending. The fibres of the lateral portion 
of the posterior roots do not remain very long in the verti- 
cal bundle, but curve forward in an horizontal plane, and in- 
this way reach the portion of the posterior cornua containing 
a fine plexus of nerve-fibres. 



AX ATOMY OF THE SPIXAL CORD. 271 

" The median (larger) portion of the posterior root-fibres 
passes to that portion of the posterior, column which bounds 
the substantia gelatinosa internally and posteriorly ; and 
curving, takes here a vertical course to pass into the poste- 
rior columns, extending chiefly upward, but perhaps down- 
ward as well. The median posterior root-fibres then undergo 
another deflection, by which they again take an horizontal 
direction, and pass to the gray substance of the posterior 
cornua, in part through the median portion and in part by 
the inner border of the substantia gelatinosa. With regard 
to the further course of the posterior root-fibres, it is impos- 
sible to present positive explanations, for the reason that the 
present methods of investigation do not afford any means of 
distinguishing the posterior fibres from the nerve-tubes in 
the vertical fasciculi of the posterior cornua, or those passing 
from the gray substance into the posterior columns, to ascend 
to the brain. The numerous divisions which the posterior 
root-fibres penetrating the posterior cornua immediately 
undergo indicate, however, that a portion of them is lost 
directly in the fine nerve-plexus of the gray substance. But 
at the same time there are numerous fibres which extend 
forward, and others which take a more or less wavy course 
toward the median line. The first, perhaps, can be regarded 
as posterior root-fibres, which pass in a forward direction in 
the nervous plexus ; the latter, on the other hand, belong to 
the commissural fibres, which cross the median line in the 
gray substance in front of and behind, the central canal. In 
my opinion, the fibres which penetrate the posterior com- 
missure are not to be regarded as belonging directly to the 
posterior roots, but are to be considered as fibres which pass 
backward to go either to the vertical fasciculi of the gray 
substance, or to pass to the brain in the posterior columns. 
If this idea be correct, and it is sustained by analogous con- 
ditions in the anterior cornua, the following view may be 
given of the course of the fibres of the posterior roots which 
penetrate the gray substance : ' A portion of the posterior 

118 



272 NEKVOUS SYSTEM. 

root-fibres, immediately after their entrance into that por- 
tion of the gray substance which contains a nerve-plexus, 
is lost in this plexus ; another portion extends farther for- 
ward, and, in proportion as the fibres pass forward, they 
likewise take part, by constant divisions, in the formation 
of the nerve-plexus. This plexus, in which larger and small- 
er nerve-cells are interspersed as it were as knotted points 
(Knotenpunkte), are in direct connection with the plexus of 
the anterior cornua. From these cells nerve-fibres arise, 
which cross the median line in the gray commissure in front 
of and behind the central canal, then curve backward, to 
pass up to the brain, in part in the vertical fasciculi of the 
posterior cornua, in part in the posterior columns, between 
both of which numerous connections may exist which are 
as yet inextricable.' This view involves a complete decus- 
sation in the spinal cord, through the fibrous elements of 
the posterior roots passing into this part. Whether this 
be in reality a complete or a partial decussation in this 
situation, a part of the fibres arising from the nerve- 
plexus passing simply backward without crossing the me- 
dian line, cannot be determined by definite anatomical in- 
vestigations ; but pathological researches, as well as the 
experimental results of that most competent observer, 
Brown-Sequard, are decidedly in favor of a complete decus- 
sation. 

" Finally, it must be admitted that two points especially 
are evident : 

u l. In the direction of the nerve-fibres which enter 
through the posterior roots, the gray substance has more 
numerous connections than in those which pass to the spi-~ 
nal cord through the anterior roots. 

" 2. The morphological distinction determinable between 
the anterior and the posterior roots is, that the former take 
their origin directly from the nerve-cells by means of the 
nerve-prolongations, while in the latter, it is only indirect 
through the nerve-plexus with the protoplasmic prolonga- 



GENERAL PROPERTIES OF THE SPINAL CORD. 273 

tions, and in this wise they are in communication with the 
nerve-cells." 

General Properties of ike Spinal Cord. 

In treating of the functions of the spinal cord, we shall 
consider, first, its general properties, as shown by direct 
stimulation of its substance in different situations ; next, its 
functions as a conductor ; and, finally, its action as a nerve- 
centre. 

The first indication that the different columns of the 
cord are possessed of different properties is to be found in 
the experiments of Magendie. This observer, however, was 
somewhat indefinite in his conclusions, particularly with re- 
gard to the anterior columns ; but he stated distinctly that 
the posterior columns are sensitive : " If we lay bare the 
cord in any portion of its extent, and if we touch, or prick 
slightly posteriorly, the two fasciculi situated between the 
posterior roots, the animal gives signs of exquisite sensibil- 
ity ; if, on the other hand, we make the same trials upon 
the anterior portion, the evidences of sensibility are scarcely 
apparent." a Since this time, numerous observers have ex- 
perimented upon the different columns, both at the surface 
and in the deep portions of the cord, with varying results. 
These observations we do not propose to discuss fully in 
detail, but will refer simply to certain of them, made within 
a few years, with the advantage of a knowledge of the 
reflex phenomena following irritation of the cord, which 
must always be taken into consideration in such experiments. 

In 1861, Chauveau, as the result of numerous experi- 
ments performed upon horses, cows, sheep, goats, rabbits, 
pigs, dogs, and cats, stated that the antero-lateral columns 
of the cord were inexcitable, both at the surface and in the 

1 GERLACH, in STRICKER, Handbuch der Lehre von den Geweben, Leipzig, 1868, 
S. 691, et seq. 

MAGEXDIE, Note sur le siege du mouvement et du sentimerd dans la moelle 
epinere. Journal de physiologic, Paris, 1823, tome iiL, p. 163. 



274 NERVOUS SYSTEM. 

deep portions. The facts upon which this assertion was 
based were, that direct stimulation of these portions of the 
cord in living animals, whether by mechanical means or by 
feeble galvanic shocks, produced no contraction of muscles 
and no pain. Upon irritating the posterior columns, either 
by mechanical or galvanic stimulus, Chauveau noted pain 
and reflex movements when the irritation was applied to the 
surface, but the results were negative when the deep por- 
tions of the columns were operated upon. The surface of 
the posterior columns seemed to possess the same general 
properties as the posterior roots of the nerves, especially 
near the roots, where the sensibility was most marked, 
gradually diminishing in intensity toward the median line ; 
but the deep portions of the cord were everywhere found 
completely insensible and inexcitable. 1 

The experiments and conclusions of Chauveau have a 
most important bearing upon the physiology of the cord, 
and are opposed to the views of the majority of physiologi- 
cal writers, though they have been admitted by some experi- 
menters. We shall discuss first the experiments upon the 
antero-lateral columns, which are most remarkable in their 
negative results. In this we shall use the term excitability 
as signifying the property of the cord which enables it to 
conduct a stimulus applied directly to it to certain muscles, 
producing convulsive movements confined to these muscles, 
and not of a reflex character. We shall apply the term 
sensibility to the property by virtue of which an irritation 
directly applied is conveyed to the brain and produces a 
painful impression. 

The experiments of Chauveau and some others upon the 
antero-lateral columns are simply negative ; but their results 
are directly opposed to those of numerous experimenters, 
who have produced local and restricted convulsive move- 
ments by direct irritation of both the superficial and the 

1 CHAUVEAU, De TexcitaUlite de la moelle epinere. Journal de la physiologic, 
Paris, 1861, tome iv., p. 369. 



GENERAL PROPERTIES OF THE SPINAL CORD. 275 

deep portions of these columns. The experiments of Lon- 
get, for example, made in 1840, have been repeatedly con- 
tinued by more recent observations. Longet exposed the 
lumbar portion of the cord in a large-sized dog and divided 
it transversely. Galvanization of the antero-lateral columns 
of the inferior portion always produced convulsive move- 
ments, while the result of irritation of the posterior columns 
was simply negative. On the other hand, galvanization of 
the posterior columns of the superior segment of the cord 
produced intense pain, and no effect followed irritation of 
the antero-lateral columns. 1 These results, being positive, 
are to be accepted in opposition to the negative results 
obtained by Chauveau, provided it can be shown that the 
stimulus did not extend from the cord to the roots of the 
nerves, a reservation which is important in all experiments 
in which the nerves are irritated with galvanism. Upon 
this point, we have some experiments, made in 1863, which 
will be detailed after we have discussed the properties of the 
posterior columns. 

With regard to the posterior columns, the views of Chau- 
veau are in advance of those of previous observers, only in 
so far as he has shown that, although the surface of this 
portion of the cord is endowed with sensibility, its deeper 
portions are entirely insensible, except in the immediate 
proximity of the posterior roots of the nerves. 

In view of the importance of the question under consid- 
eration, and of the contradictory results of experiments, we 
repeated, in 1863, the experiments of Chauveau, under con- 
ditions as nearly physiological as possible. We had often 
had occasion to note the diminished sensibility of the roots 
of the spinal nerves immediately following the very severe 
operation of opening the spinal canal, and had also noted 
that the sensibility increased, probably approaching the nor- 
mal standard, after the animal had been allowed a few hours 

1 LONGET, Anatomic ft physiologie du systeme nerveux, Paris, 1842, tome i., 
p. 272, et seq. 



276 NERVOUS SYSTEM. 

of repose. For this reason, we made our observation about 
two hours after the first operation. To avoid the suspicion 
of an extension of the galvanic current beyond the portion 
of the cord which we desired to stimulate, the irritation was 
first made by simply scratching the parts with the point of 
a needle. The following experiment is the type of several, 
in all of which the results were identical : 

May 28, 1863, at 1 P. M., the laminae and the spinous 
processes of the three lower lumbar vertebrae were removed 
from a medium-sized dog. There was no very great haem- 
orrhage. The spinal cord and the roots of three of the 
nerves were exposed, and the wound was then closed. The 
operation was performed with the animal under the influ- 
ence of ether, and lasted about three-quarters of an hour. 

About two hours after the first operation, the animal was 
brought before the class at the Long Island College Hospi- 
tal. The wound was opened, and the properties of the an- 
terior and posterior roots were demonstrated. The follow- 
ing observations were then made on the spinal cord : 

The external surface of the posterior columns was irri 
tated by scratching with the point of a needle. This pro- 
duced pain, the more marked, the nearer the irritation was 
brought to the origin of the posterior roots. The surface 
was almost insensible at the median line. A feeble galvanic 
stimulus was then applied by means of a plnce electrique, 
with the same results. The deep portions of. the posterior 
columns were then irritated without effect. 

The cord was then divided transversely, and mechanical 
and galvanic stimulus were applied to the cut surfaces. 

The surface of the upper end of the cord was irritated 
with the needle, and the needle was plunged deeply into its 
substance, without effect. The same negative results fol- 
lowed application of the galvanic stimulus. 

The lower end of the cord was then elevated with a hook, 
and the surface of the anterior columns was irritated by the 
needle and by galvanism. The invariable effect was con- 



GENERAL PROPERTIES OF THE SPINAL CORD. 277 

vulsive movements in the lower extremities, without pain. 
The same irritation was applied to the deep portions of the 
anterior columns with like results ; i. e., convulsive move- 
ments in the lower extremities, following the irritation im- 
mediately. 

The above-mentioned phenomena were fully verified by 
repeated experiments, and the animal was then killed by 
section of the medulla obloiigata. 

The general movements accompanied by evidences of 
pain were readily distinguishable from the local convulsive 
movements with no pain. 

This experiment fully confirms the observations of Chau- 
veau with regard to the posterior columns, but shows, in 
opposition to Chauveau, that the anterior columns are ex- 
citable, both at the surface and in the deep portions. The 
recent observations of Yulpian are also opposed to the re- 
sults obtained by Chauveau with regard to the antero-lat- 
eral columns. From a number of carefully-executed experi- 
ments, Yulpian draws the following conclusions : 

" 1 . The gray substance is absolutely inexcitable. 

"2. The anterior fasciculi possess a certain degree of 
motor excitability. 

"3. There is no doubt that the posterior fasciculi are 
very excitable. They are sensitive and excito-motor if the 
cord be left intact, and simply excito-motor if the cord be 
divided transversely and separated from the encephalon. It 
is the same, but to a less degree, in that portion of the lat- 
eral fasciculi contiguous to the posterior fasciculi." 1 

In the face of definite and positive experiments showing 
the excitability of certain portions of the cord, it is impos- 
sible to accept the purely negative results obtained by Chau- 
veau and others. This remark applies to recent experi- 
ments made by Huizinga, carrying out the observations of 
Yan Deen, in which he assumes to show that the anterior 

1 YULPIAX, Lemons sur la physiologic generate et comparee da systeme nerveitx, 
Paris, 1866, p. 362. 



278 NERVOUS SYSTEM. 

columns are not excitable, even near the roots of the nerves ; 
and that when convulsive movements follow galvanization 
near the roots, this is due to an extension of the current to 
the roots themselves. 1 

As the result of the most definite and reliable experi- 
ments of others, bearing upon the question of the properties 
of the cord, and of our own observations, we have arrived 
at the following conclusions : 

The gray substance is probably inexcitable and insensible 
under direct stimulation. 

The antero-lateral columns are insensible, but are excita- 
ble both on the surface and in their substance ; i. e., direct 
stimulation will produce convulsive movements in certain 
muscles, which movements are not reflex and are not attend- 
ed with pain. The lateral columns are less excitable than 
the anterior columns. 

The surface, at least, of the posterior columns is very 
sensitive, especially near the posterior roots of the nerves. 
The deep portions of the posterior columns are probably in- 
sensible, except very near the origin of the nerves. 

The above conclusions refer only to the general proper- 
ties of different portions of the cord, as shown by direct 
stimulation, in the same way that we demonstrate the gen- 
eral properties of the nerves in their course. In all proba- 
bility, the fibres in the white and gray substance of the cen- 
tral nervous system conduct motor stimulus from the brain 
and sensory impressions to the brain, while they are them- 
selves insensible and inexcitable under direct stimulation. 
The physiological action of the cord as a conductor, one of 
the most interesting and important of its functions, will be 
fully considered in another chapter. 

1 HUIZINGA, Die Unerregbarkeit der vorderen RucJcenmarkstrange.Archiv 
fur die gesammte Physiologic, Bonn, 1870, Bd. Hi., S. 81, et seq. 



CHAPTER X. 

ACTION OF THE SPINAL CORD AS A CONDUCTOR. 

Transmission of motor stimulus in the cord Decussation of the motor conduct- 
ors of the cord Decussation at the medulla oblongata Decussation of the 
motor conductors in the cervical portion of the cord Transmission of sen- 
sory impressions in the cord The white substance of the posterior columns 
does not conduct sensory impressions Action of the gray matter as a 
conductor Probable function of the cord in connection with muscular 
coordination Decussation of the sensory conductors of the cord Summary 
of the action of the cord as a conductor. 

IN treating of the functions of the spinal cord, both as a 
conductor and as a nerve-centre, we shall endeavor to discuss 
those facts only which are, it is to be hoped, either defini- 
tively settled, or are in accordance with what is at present 
known in anatomy, physiology, and pathology. The litera- 
ture upon this portion of our subject is so extended and 
diffuse, that a full, critical analysis of the different experi- 
ments and views that have been presented since the obser- 
vations of Magendie, in 1823, would inevitably complicate 
and confuse our description. "We shall give citations, how- 
ever, which will enable the reader to refer readily to the 
most reliable historical and controversial discussions upon 
this subject. 1 

1 Longet, in his treatise on physiology, gives a tolerably complete historical 
account of the numerous experimental researches concerning the functions of 
the cord as a conductor ( Traite de physiologic, Paris, 1869, tome iii., p. 338, et seq.\ 
The writings upon this subject by Brown-Sequard are very voluminous, and are 
scattered through numerous periodical publications, while many of his papers 
are controversial, and are reiterations of experiments and views previously pub- 



280 NERVOUS SYSTEM. 

Transmission of Motor Stimulus in the Cord. The 
antero-lateral columns of the cord, both the white and the 
gray substance, are entirely insensible to direct irritation, 
and conduct the motor stimulus from the centres to the 
periphery. This statement may be accepted, as the result 
of positive demonstration, with very little qualification. 

If the posterior columns of the cord be divided or even 
removed for a certain length, the animal retains the power 
of voluntary motion intact. It is supposed by Dr. Brown- 
Sequard that the white substance of the antero-lateral col- 
umns, in addition to its motor properties, takes a slight but 
well-defined part in the transmission of sensory impressions, 
and this idea is based upon experiments which seem to show 
that slight sensibility remains in the lower extremities after 
section of the posterior columns. 1 Such experiments, how- 
ever, must be accepted with a certain degree of reserve, in 
view of the great difficulty of dividing the columns sepa- 
rately. If the white substance of the antero-lateral columns 
take any part in the conduction of sensory impressions, it is 
slight and unimportant. On the other hand, if the antero- 
lateral columns of the cord be divided on both sides, the 
power of voluntary motion is lost absolutely in all parts sup- 
plied with nerves coming from the cord below the section. 

It would be an interesting point to determine positively 
the relative importance of the white and the gray substance 
of the anterior columns in the transmission of motor stimu- 
lus ; but this has thus far been impossible. We cannot with 
certainty divide the gray matter of the anterior columns 
completely and leave the white substance intact, nor can we 
divide the white substance without injuring the gray. As 
far as experiments go, however, they seem to show that 

lished. A list of his most important memoirs, with a short account of his ex- 
periments and conclusions, is given in the Journal de la physiologic, Paris, 1862, 
tome v., p. 641, et seq. 

1 BROWN-SEQUARD, JErcperimces montrant que les cordons anterieurs de la moelle 
epinere servent d la transmission des impressions sensitives. Journal de la physi- 

ie, Paris, 1858, tome i., p. 809. 



MOTOR CONDUCTION IN THE SPINAL COED. 281 

transmission is not effected exclusively by the white sub- 
stance, but that the gray matter plays an important part in 
this function. 1 "We shall refer, farther on, to the action of the 
gray substance in the transmission of sensory impressions. 

It is evident, from anatomical facts as well as from the 
results of direct experimentation, that the fibres of conduc- 
tion of motor stimulus pass from the brain to the anterior 
roots of the nerves, through the spinal cord, from above 
downward, and that there is no other medium for the trans- 
mission of the will to the muscles. Wherever the cord 
be divided, all the muscles supplied by nerves given off be- 
low the section are paralyzed. From the brachial enlarge- 
ment of the cord, nerves of motion pass to the superior ex- 
tremities, and the inferior extremities are supplied mainly 
by nerves coming from the lumbar enlargement. The di- 
rection of these motor fibres in the cord itself has only 
been elucidated by experiments upon living animals. If the 
anterior columns alone be divided in the dorsal region, there 
is almost complete paralysis of the lower extremities. If the 
lateral columns be divided in this situation, without injuring 
the anterior columns, voluntary movements of the lower ex- 
tremities are diminished, but are not abolished. If the an- 
terior columns be divided high up in the cervical region, 
there is a diminution in the voluntary movements, but by 
no means so marked as when the section is made in the dor- 
sal region ; but if the lateral columns be divided in the upper 
cervical region, the paralysis is almost or quite complete. 2 

The experiments just cited clearly show that the situa- 
tion of the chief motor conductors of the cord is different in 
the dorsal and in the cervical region. In the dorsal region, 
while conduction of the motor stimulus takes place through 
fibres contained both in the anterior and in the lateral 

1 YULPIAN, Lemons sur la physiologie generate et comparee du systeme nerveux, 
Paris, 1866, p. 369. 

2 BROWX-SEQUARD, Physiology and Pathology of the Central Nervous System, 
Philadelphia, 1860, p. 46. VULPIAN, Systeme nerveux, Paris, 1866, p. 370. 



282 NERVOUS SYSTEM. 

columns, the transmission is mainly through the anterior 
columns, the lateral columns being much less important. 
In the cervical region, the conditions are reversed, tad the 
conduction takes place chiefly by means of the lateral col- 
umns. Passing from above downward, therefore, the motor 
fibres are situated in the cervical region mainly in the lateral 
columns ; but progressively, as they pass through the dorsal 
and the lumbar portions of the cord, these fibres change 
their location and are found chiefly in the anterior col- 
umns. 

llecent observations have not sustained the old idea that 
the lateral columns of the cord contain fibres which preside 
specially over the movements of the thorax. The experi- 
ments of Yulpian upon this point are conclusive. If the 
lateral column be divided on one side at about the third or 
fourth cervical vertebra, there is considerable enfeeblement 
of the muscles of the thorax upon the corresponding side, 
but there is also partial loss of power in the limbs, which is 
more marked in the anterior extremity. This diminution 
in pow r er in the thoracic muscles is such, that in ordinary 
tranquil respiration, the side corresponding to the section 
does not move ; but in difficult respiration, or in crying, the 
movements are very marked. 

Decussation of the Motor Conductors of the Cord. Well- 
established anatomical and pathological facts show conclu- 
sively that there is a complete decussation of the motor con- 
ductors of the cord ; so that the stimulus of volition gen- 
erated in one lateral half of the brain always passes to the 
opposite half of the body. If a lesion occur in the brain 
upon one side, so as to produce total paralysis of motion, the 
opposite side of the body is paralyzed, while voluntary mo- 
tion is absolutely intact on the side corresponding to the 
injury. In the anterior pyramids of the medulla oblongata, 

1 VULPIAN, Systeme nerveux, Paris, 1866, p. 371. 



MOTOE COXDUCTIOJr IN" THE SPINAL CORD. 283 

the decnssation of the fibres is easily demonstrated ana- 
tomically. In view of these facts, concerning which there 
is no difference of opinion, it only remains to show by 
physiological experiments that decussation actually takes 
place at the medulla oblongata, and to submit to the same 
method of inquiry the following important question : Assum- 
ing that crossing of motor fibres takes place at the medulla, 
is this the sole seat of decussation of these fibres, or does it 
also exist in certain portions of the cord below ? 

The question of decussation at the medulla oblongata is 
easily answered. In the first place, we have the crossed ac- 
tion in hemiplegia and the easy anatomical demonstration 
of the decussating fibres. The experimental confirmation 
of these facts is not so simple, for the reason that animals 
survive operations upon the medulla oblongata for a very 
short time. As far as can be learned, however, from the 
latter mode of inquiry, the conclusions drawn from anatomy 
and pathology are fully sustained. If the medulla be ex- 
posed in a living animal, and " if a section is made longitu- 
dinally just at the place of the decussation of the anterior 
pyramids, so as to divide completely all of the decussating 
elements, we find that, although the animal lives some time 
after the operation, it has no voluntary movement at all in 
any of the limbs, which are almost always the seat of con- 
vulsions." l 

The question of decussation of motor fibres in the cord 
itself is one which can be settled only by physiological ex- 
periments, as the course of the decussating fibres, if they 
exist, cannot be demonstrated anatomically. It is remark- 
able that Galen submitted this point to experimental inves- 
tigation, by dividing the cord longitudinally in the median 
line in the lumbar region. This operation was not followed 
by loss of voluntary power in the lower extremities, show- 
ing that the motor fibres do not cross the median line, at 

1 BROWN-SEQUARD, Physiology and Pathology of the Central Nervous System, 
Philadelphia, 1860, p. 49. 



284 NERVOUS SYSTEM. 

least in this portion of the cord. 1 Recent experiments upon 
the cervical portions of the cord show that there is a very 
slight decussation of motor fibres in this situation. The first 
observations pointing to this conclusion are those of Brown- 
Sequard. " There is always, even in mammals, after a trans- 
versal section of the whole or a lateral half of the spinal cord, 
at least some appearance of voluntary movements in the side 
of the injury, and always also a diminution of voluntary move- 
ments in the opposite side ; so that, in animals, there seems 
to be in the spinal cord a decussation of a few of the volun- 
tary motor conductors. As there seems to be no such decus- 
sation in man, at least according to several pathological facts, 
we shall not insist upon its existence in animals." 2 

Yan Kempen has repeated and extended the very re- 
markable experiment of Galen, with the most satisfactory 
rosults. This observer made a median, longitudinal section 
of the cord in dogs and rabbits, at the site of the fifth, sixth, 
and seventh cervical vertebrae. " This experiment was fol- 
lowed by partial paralysis of voluntary movements in the 
posterior extremities, so that the animal thus operated upon 
moved the posterior limbs and was able to change his posi- 
tion, without, however, being able to raise himself." 3 

As there is some difference in the results of observations 
upon different animals, and as decussating motor fibres have 
never been demonstrated in man, it is impossible to apply 
the above experiments without reserve to the human sub- 
ject ; but they show, nevertheless, that, in mammals, the 
motor columns of the cord probably do not decussate in the 

1 GALENUS, De Anatomicis Administrationibm, Liber viii., Cap. vi. Opera 
omnia, Lipsiae, 1821, tomus ii., p. 683. 

These remarkable experiments must have been made in the latter half of the 
second century, as Galen was born in 131, and died about the year 200. 

2 BROWN-SEQUARD, Physiclogy and Pathology of the Central Nervous System, 
Philadelphia, 1860 ? p. 48. 

8 VAN KEMPEN, Experiences physiologiques sur la transmission de la semibilite 
et du mouvement dans la moelle epinere. Journa 7 de la physiologic, Paris, 1 859, 
tome ii., p. 528. 



SENSOKY CONDUCTION IN THE SPINAL CORD. 255 

dorso-lumbar region ; that partial decussation occurs in the 
cervical region ; and that 1 the decussation is completed in 
the anterior pyramids of the medulla oblongata. 

Transmission of Sensory Impressions in the Cord. 
There is very little room for discussion concerning what is 
positively known with regard to the transmission of sensory 
impressions in the cord, though there are some portions of 
its structure, the action of which in conduction is still ob- 
scure. Early in the physiological history of this portion of 
the nervous system, Longet made a number of experiments, 
which seemed to show that the posterior columns of the cord 
were the conductors of sensory impressions to the brain, and 
that the antero-lateral columns transmitted the motor stim- 
ulus. These have been already referred to in connection 
with the properties of the cord. They were made by apply- 
ing a stimulus directly to the cord itself. Longet discredited 
observations made by dividing different portions of the cord, 
for the reason that he supposed that the mere operation of 
exposing the cord and of removing the dura mater was 
followed by a depression of the nervous action sufficient to 
render the evidences of sensibility in the lower extremities 
scarcely appreciable. 1 The conclusions drawn from these 
experiments were at first accepted by nearly all physiologi- 
cal writers, and it was generally admitted that the transmis- 
sion of sensory impressions was effected solely by the pos- 
terior columns. It was found that the gray matter of the 
cord was both insensible and inexcitable, and the conduction 
was supposed to take place exclusively through the white 
substance. The views of Longet were in direct opposition 
to those of Bellingeri, who claimed, in 1823, to have demon- 
strated by experiment, that sensory impressions were con- 
veyed to the brain exclusively by the gray substance of 
the cord, and that sensibility persisted in the lower ex- 

1 LONGET, Anatomic et physiologic du tysteme nerveux, Paris, 1842, tome i., 
p. 276. 



286 NEKVOUS SYSTEM. 

trcmitics after complete section of the posterior white col- 
umns. 1 

At the time the above-mentioned experiments were 
made, our knowledge of the properties of the cord was very 
incomplete, and it was difficult to understand how any of 
its fibres could conduct sensory impressions and yet be in- 
sensible to direct stimulation ; but now we know that the 
gray matter does act as a conductor, and yet it is certainly 
insensible. The simple questions now to be determined are 
the following : 

1. Does or does not the white substance of the posterior 
columns of the cord conduct sensory impressions to the 
brain ? 

2. Does the entire gray substance of the cord act as a 
conductor of sensation ? 

3. Do both the gray matter of the cord and the white 
substance of the posterior columns act as conductors, or 
does either one act to the exclusion of the other ? 

These questions may now be considered as definitively 
answered by the most positive and unmistakable results of 
experiments upon living animals, which, while they render 
the precise function of the white substance of the posterior 
columns a matter of conjecture, leave no doubt with regard 
to t!he parts of the cord which act as conductors of sensory 
impressions. This statement is based upon the researches 
of Brown-Sequard, whose experiments upon this subject 
have been often confirmed and never successfully contra- 
dicted. 

The experimental answer to the first question is capable 
of but one construction. If the white substance of both 
posterior columns be divided, the sensibility of the posterior 
extremities is not diminished, at least as far as can be shown 

1 BELLINGERT, De Medulla, Spinali Nervisgiie ex ea prodeuntibus, Annolationes 
Anatomico-Physiologicce, Lectce a die Sjanuarii 1822 ad ZQjanuarii 1823, p. 237 ; 
Experimenta Physiologica in Medullem Spinalem habita, Lecta die 13 junii 1824, 
p. 311;' and LONGET, op. cit., tome iii., p. 341. 



SENSOEY CONDUCTION IN THE SPINAL COKD. 287 

by experiments upon animals, in which these points are al- 
ways difficult of determination. On the other hand, if every 
portion of the cord be divided except the posterior columns, 
sensibility is completely lost in the parts below the section. 
The accuracy of these results cannot be called in question, 
especially when controlled by experiments showing the con- 
ducting properties of the gray substance of the cord ; and 
they show that, whatever may be the functions of the poste- 
rior white columns, they do not serve as conductors of sen- 
sory impressions. 1 

The second question admits of an equally positive an- 
swer from the results of experimental inquiry. If the entire 
substance of the cord, except the posterior columns of white 
matter, be divided transversely, as we have just seen, sensi- 
bility is abolished in all parts below the section ; but, as we 
have stated in treating of the transmission of motor stimu- 
lus by the cord, voluntary motion is also destroyed. 11 Ex- 
periments show, farthermore, that sensory impressions are 
conveyed exclusively by the gray substance. " If the ante- 
rior, the lateral, and the posterior columns of the spinal cord 

1 The experiments by Brown-Sequard, which have led to the above conclu- 
sion, are of the most positive and satisfactory character (Physiology and Pathol- 
ogy of the Central Nervous System, Philadelphia, 1860, p. 19), and have been 
repeatedly confirmed by himself and other observers, among the most promi- 
nent of whom are Yulpian and Philipeaux (VULPIAX, Systeme nerveux, Paris, 
1866, p. 373). The most important experiments in opposkion are those of 
Schiff, quoted and adopted by Longet, by which Longet endeavors to prove that 
the posterior columns are conductors of the tactile sense (LONGET, Traite de 
physiologic, Paris, 1869, tome iii., p. 353). In these experiments, the antero- 
lateral columns were divided, and the animal was afterward enfeebled by a copi- 
ous haemorrhage. Upon pinching the tail, the animal gave evidence of sensa- 
tion, but suffered no pain, even when the sciatic nerve was bruised or torn. In 
these observations, it was not shown that the entire gray substance was divided, 
and the experiments after copious haemorrhage were certainly not made under 
strictly physiological conditions. It is well known, also, that if a small portion 
of gray matter be undivided, there is conduction of sensory impressions. In all 
of Brown-Sequard's experiments, the exact h'mits of the sections of the cord 
were ascertained by subsequent examination of the parts hardened in alcoboL 

8 See page 280. 

119 




SDICAL * 

f Y r> r> T^^.r 



288 NEKVOUS SYSTEM. 

are divided transversely, at the dorsal region, one set at one 
place, another at a distance of one or two inches, and the 
third also at the same distance from the second, so that the 
only channel of communication between the posterior limbs 
and the sensorium is the gray matter, of which, however, 
several parts have, unavoidably, been divided (such as the 
anterior and the posterior gray cornua, and also more or less 
of the central gray matter), we find that the posterior limbs 
are still sensitive, though evidently less than in the normal 
condition." 

It is impossible to divide the gray matter of the cord 
alone, without injuring, more or less, the white substance ; 
but when the gray matter is divided with very slight injury 
of the white substance, sensibility in the parts below the 
point of section is totally destroyed. 3 As regards the part 
of the gray substance specially concerned in the transmis- 
sion of sensory impressions, the results of experimental in- 
vestigation have not been so definite ; but Browii-Sequard 
is of the opinion that the transmission takes place chiefly in 
the gray matter surrounding the central canal, while it may 
also occur to some extent in other portions. 3 

The answer to the third question is deduced from the 
answers to the first two. The gray matter and the white 
substance of the cord do not participate in the transmission 
of sensory impressions, this being effected by the gray sub- 
stance, especially its central portion, to the exclusion of the 
white. 

The precise office of the posterior white columns of the 
cord is still a matter of conjecture. If these parts be insen- 
sible, except on the surface and near the posterior roots of 
the nerves, and if they take no part in the transmission of 
sensory impressions to the brain, which seems to have been 
conclusively proven, what is their function ? 

1 BROWN-SEQUARD, Physiology and Pathology of the Central Nervous System, 
Philadelphia, 1860, p. 22. 

8 VULPIAN, Systeme nerveux, Paris, 1866, p. 374. 3 Op. cit., p. 23. 



MTJSCITLAR COORDINATION. 289 

The anatomical relations of the posterior white columns, 
the results of experiments upon living animals, and certain 
well-marked pathological phenomena, point very strongly to 
a connection between these columns and the coordination 
of muscular movements. 

Probable Function of the Cord in Connection with Mus- 
cular Coordination. Anatomists have not been able to trace 
satisfactorily the direction of all of the fibres contained in the 
posterior columns ; but it is probable that at least some of 
these fibres serve as longitudinal commissures, and connect 
together the nerve-cells, extending for a greater or less dis- 
tance both upward and downward in the cord. This ana- 
tomical arrangement is rendered probable chiefly by the re- 
sults of experiments. 

If the posterior columns be completely divided, by two or 
three sections made at intervals of from three-fourths of an 
inch to an inch and a quarter, the most prominent effect is 
a remarkable trouble in locomotion, consisting in a want of 
proper coordination of movements. These important ex- 
perimental results were obtained by Yulpian. 1 

In the remarkable disease known under the name of 
locomotor ataxia, 2 there is a very peculiar condition of the 
muscular system, in which, while the power of the muscles 
is but slightly diminished, the movements of progression 
show great deficiency in coordinating power, frequently at- 
tended with more or less disturbance in the sensibility of the 
parts affected. These symptoms are associated with struc- 
tural disease of the cord, limited to the posterior columns 
and the posterior roots of the spinal nerves. 

Many years ago, before locomotor ataxia had been gener- 
ally recognized by pathologists, Todd made the following re- 
markable statement with regard to the posterior columns : 

1 YULPIAX, Systeme nerveux, Paris, 1866, p. 381. 

8 For a description of this disease, see, HAMMOND, Diseases of the Nervous 
System, New York, 1871, p. 484, et seq. 



290 NERVOUS SYSTEM. 

"I have long been impressed with the opinion, that the 
office of the posterior columns of the spinal cord is very dif- 
ferent from any yet assigned to them. Theyjnay be in part 
commissural between the several segments of the cord, serv- 
ing to unite them and harmonize them in their various ac- 
tions, and in part subservient to the function of the cerebel- 
lum in regulating and coordinating the movements necessary 
for perfect locomotion." l Todd further states, that this view 
is supported by the phenomena observed in cases of disease 
" distinguished by a diminution or total loss of the power of 
coordinating movements. ... In two examples of this va- 
riety of paralysis, I ventured to predict disease of the poste- 
rior columns, the diagnosis being founded upon the view^s 
of their functions which I now advocate ; and this was found 
to exist on post-mortem inspection ; and in looking through 
the accounts of recorded cases in which the posterior col- 
umns were the seat of lesion, all seem to have commenced 
by evincing more or less disturbance of the locomotive pow- 
ers, sensation being affected only when the morbid change 
of structure extended to and more or less involved the pos- 
terior roots of the spinal nerves." 3 

It is only necessary to add that the views of Todd have 
been in the main confirmed in the numerous cases of loco- 
motor ataxia that have lately been so fully described by 
pathologists ; and, from these facts, it is more than probable 
that the posterior columns contain fibres connecting the dif- 
ferent segments of the cord, and that they play an important 
part in the coordination of muscular movements. The gen- 
eral function of coordination will be again considered in con- 
nection with the cerebellum. 

Decussation of the Sensory Conductors of the Cord. In 
hemiplegia due to injury of the brain, the paralysis occurs 

1 TODD, Cyclopcedia of Anatomy and Physiology, London, 1839-1847, vol. Hi., 
p. 721, Q, Article, Nervous System. 
9 Op. *., p. 721, R. 



DECUSSATTOF OF, THE SENSORY CONDUCTOKS. 291 

upon the side of the body opposite to the cerebral lesion. 
The phenomena ordinarily observed are simply paralysis of 
motion ; but in those cases in which both motion and sensa- 
tion are abolished upon one side of the body, the lesion in 
the brain is found to be upon the opposite side. It is evi- 
dent, therefore, that there is a decussation of the conductors 
of sensory impressions as well as of the conductors of the mo- 
tor stimulus. 

As early as 1822, Fodera made a longitudinal section of 
the spinal cord in the lumbar region, exactly in the median 
line. In this experiment, " sensation was destroyed, and in 
part motion upon the two sides." * Inasmuch as in this sec- 
tion it is only possible to divide the fibres, passing from one 
lateral half of the cord to the other, it is evident that the 
sensory conductors must decussate in the spinal cord itself. 
As far as we know, this is the first experiment pointing to 
the decussation of sensory fibres in the cord, the observations 
of Galen, to which we have already referred, being limited 
to the phenomena of motion. 3 

The next experiments bearing upon the decussation of 
the sensory conductors in the cord are those of Yan Deen. 
Among the numerous observations made upon the spinal 
cord by this physiologist, are one or two in which he noted 
the fact that, after section of one lateral half of the cord in 
the frog, at the site to the third dorsal vertebra, " the animal 
had no real loss of sensibility in the posterior extremity on 
the side on which the half of the spinal cord had been cut." 3 
Although Yan Deen did not distinctly state, as a conclusion 
drawn from these observations, that there is decussation of 
the sensory conductors in the cord, the fact of section of one 
lateral half of the cord with no loss of sensation on the cor- 

1 FODERA, Recherches experimentales sur le systeme nerveux, presentees d 
T Academic des sciences, le 31 decembre, 1822. Journal de phy&dogie, Paris, 1823, 
tome ill, p. 199. 

9 See page 284. 

3 VAN BEEN, Traiies et decouvertes sur la physiologic de la moette epinere, 
Leide, 1841, pp. 65, 92. 



292 NERVOUS SYSTEM. 

responding side of the body remains as one of the first ex- 
perimental arguments in favor of the crossed action. 

Experiments upon living animals as well as pathological 
facts show that, after section or injury confined to one lateral 
half of the cord, the general sensibility upon the correspond- 
ing side of the body is very much exaggerated, producing a 
condition of well-marked hypersesthesia. This remarkable 
fact was distinctly noted by Fodera, in 1822: "Having di- 
vided, in a Guinea-pig, the right superior column of the cord 
in the middle of the dorsal region, the sensibility of the flank 
and of the posterior extremity of the same side was more 
exquisite than in every other part of the body, and it seemed 
that the movements of the same extremity possessed greater 
energy." ] This observation was confirmed, and the experi- 
ments were very much extended, by Brown-Sequard. 2 Cases 
presenting the same phenomena have also been observed in 
the human subject, when one side of the cord has been in- 
vaded by disease. 3 

Physiologists are at a loss to explain the hypersesthesia 
which follows section of the sensory conductors of the cord, 
but the fact nevertheless remains. The exaggeration of sen- 
sibility is not due to section of certain fibres, which might 
be supposed to increase the impressibility of the remaining 
fibres, for, as was shown by Yulpian, it is sufficient to prick 
with a pin one of the lateral halves of the cord to observe 
these remarkable phenomena. 4 "With these few words, we 
will leave the subject of hypersesthesia from injury to the 
cord, and pass to the crossed action of its sensory con- 
ductors. 5 

1 FODERA, Journal de physiologic, Paris, 1823, tome iii., p. 200. 

2 BROWN-SEQUARD, Experimental Researches applied to Physiology and Pathol- 
ogy, New York, 1853, p. 64, el al 

3 BROWN-SEQUARD, Recherches sur la transmission des impressions de tad, de 
chatouillement, de douleur, de temperature et de contraction (sens musculaire) dans 
let moette epinere. Journal de la physiologie, Paris, 1863, tome vi., p. 645. 

4 VULPIAN, Systeme nerveux, Paris, 1866, p. 388. 

5 For further experiments showing the effects of transverse section of the 



DECUSSATIOX OF THE SENSORY CONDUCTOES. 293 

In treating of the cord as a conductor of sensory impres- 
sions, we have already shown that this function is performed 
by the gray substance alone. "We have also seen, in connec- 
tion with the phenomena of conduction of the motor stimu- 
lus, that this is effected by the antero-lateral columns, which 
do not act as sensoiy conductors, except by virtue of their 
gray matter. As it is impossible to divide the gray matter 
with certainty without injuring the white substance, and as 
we are fully acquainted with the motor properties of the 
cord, we are prepared to comprehend the effects upon con- 
duction of sensory impressions which follow division of one 
or the other lateral half. In our detail of experiments, we 
will not consider the phenomena of hypersesthesia, but con- 
fine ourselves to the loss or diminution of sensibility. 

Brown-Sequard was the first to demonstrate decussation 
of the sensory conductors in the cord itself ; and, although 
his experiments upon this subject are almost innumerable, 
and his writings, scattered, voluminous, and sometimes not 
free from the obscurity due to unnecessary refinement and 
elaborateness of detail, the main facts can be expressed in 
a very few words ; and he may justly be said to have created 
the physiology of the sensory conductors. 

Brown-Sequard repeated the experiments of Galen and 
of Fodera, dividing the cord longitudinally in the median 
line, producing complete paralysis of sensation on both sides 
in all the parts below the section. By this operation, if the 
section had been made accurately in the median line, the 
only fibres that could be divided were those passing from 
one side of the cord to the other. 

The second experimental proof of the decussation of sen- 
sory fibres consists in transverse section of one or the other 
of the lateral halves of the cord. If one lateral half of the 
cord be divided, sensibility is abolished in the parts below 

cord in its posterior portion, see, BROWN-SEQUARD, Nouvelles recherches sur la 
physiologic de la moelle epinere. Journal de la physiologic, Paris, 1858, tome i., 
p. 139. 



294: NERVOUS SYSTEM. 

the section upon the opposite side of the body. 'In an article 
published in 1858, Brown-Sequard details very succinctly an 
experiment showing this fact, though his first experiments 
were made in 1849. 1 He denuded the cord in the lumbar 
region in a vigorous dog, and made sections upon one side, 
progressively deeper and deeper, from without inward. 
When the section included about one-third of the lateral 
half, the sensibility seemed slightly augmented upon the 
opposite side. This section involved only a part of the lat- 
eral white column and a small portion of the anterior cornu 
of gray matter. When the section was extended so as to 
involve about two-thirds of the lateral half, the sensibility 
was notably diminished upon the opposite side. When the 
section extended to the median line, the sensibility was very 
much diminished ; and when it extended just beyond the 
median line, it was entirely abolished upon the opposite 
side. 2 These observations, and others of the same nature, 
show conclusively that in the animals experimented upon, 
at least, there is a decussation of the greatest part of the 
sensory conductors in the cord itself. 

The course of the fibres in their decussation is indicated 
by further experiments, which show that the sensitive fibres 
from the posterior roots of the nerves " pass along the poste- 
rior columns only a little way, and leave them to enter the 
central gray matter." ' It is undoubtedly in this gray sub- 
stance that they pass from one side to the other, probably 
through the cell-prolongations. The fact that the fibres pass 
in the cord a short distance before they decussate, and that 
they pass downward as well as upward, is well shown by the 
following experiment : 

" If we divide transversely a lateral half of the spinal 

1 See list of works, in the Journal de la ph^siologie, Paris, 1862, tome v., 
p. 646, No. 44. 

2 BROWN-SEQUARD, Nouvelles recherches sur la physiologic de la moelle epinere. 
Journal de la physiologie, Paris, 1858, tome L, p. 139, et seq. 

8 BROWN-SEQUARD, Physiology and Pathology of the Central Nervous System. 
Philadelphia, 1860, p. 25. 



SUMMARY -OF THE SPINAL COED. 295 

cord in two places, so as to have three pairs of nerves be- 
tween the two sections, we find that the middle pair has 
almost the same degree of sensibility as if nothing had been 
done to the spinal cord, while the two other pairs have a 
diminished sensibility, the upper one particularly in its upper 
roots, and the lower one in its lower roots ; which facts seein 
to show that the ascending fibres of the upper pair, and the 
descending fibres of the lower one, have been divided before 
they had made their decussation. 

If there is only one pair of nerves between two sections, 
its sensibility is almost entirely lost, as then the transversal 
fibres are almost alone uninjured (most of the ascending and 
descending being divided), which fibres are employed for 
reflex action, and hardly for the transmission of sensitive 
impressions." l 

The experimental facts just cited conclusively show de- 
cussation of sensory conductors in the cord in the animals 
operated upon, and this has been sufficiently confirmed by 
other experimenters to render the fact certain. It is possi- 
ble that the decussation may not be so complete in some 
other classes of animals, which would account for the results 
obtained by those who have denied decussation ; but cases 
of disease of the cord in the human subject all go to show 
that the crossed action is complete in man. 

/Summary of the Action of the Spinal Cord as a Conductor. 

The antero-lateral columns of the cord, comprising that 
portion included between the anterior median fissure and the 
origin of the posterior roots of the nerves, are insensible to 
direct irritation, and serve as conductors of the motor stimu- 
lus from the brain to the anterior roots of the nerves. If 
these columns be divided, voluntary motion is lost in all 
parts below the section. If the rest of the cord be divided, 
leaving the antero-lateral columns intact, the power of volun- 

1 BROWX-SEQUARD, Central Nervous System, Philadelphia, 1860, p. 36. 



296 NEKVOUS SYSTEM. 

tary motion remains. Throughout the greater part of the 
cord, this action is direct, and division of the antero-lateral 
columns on one side produces paralysis of motion on the cor- 
responding side of the body. There is a decussation of the 
motor fibres at the medulla oblongata, and a partial decussa- 
tion in the cord itself in the upper cervical region. In the 
dorsal region and below, the motor conducting fibres are 
situated chiefly in the anterior columns ; but in the cervical 
region, these fibres pass to the sides and are contained chiefly 
in the lateral columns. The conduction of motor stimulus 
is probably not effected exclusively by the white substance, 
but is transmitted in part by the gray matter. 

The gray substance of the cord serves as the medium of 
transmission of sensory impressions to the brain. This is 
effected chiefly by the gray matter surrounding the central 
canal, but it may take place to some extent in other portions. 
If the entire gray matter be divided, with but slight injury 
to the white substance, sensation is lost in all parts situated 
below the section. The white substance does not conduct 
sensory impressions to the brain, either in the antero-lateral 
or the posterior columns. The most probable function of 
the white substance of the posterior columns is to unite 
the different segments of the cord together by longitu- 
dinal commissural fibres ; and this portion of the cord has 
an important influence in coordinating the muscular move- 
ments. 

The sensitive nerve-fibres from the posterior roots of the 
spinal nerves pass in the cord for a short distance upward 
and downward. They then penetrate the gray matter, and 
decussate throughout the entire length of the cord. Divis- 
ion of one lateral hah of the cord is followed by complete 
paralysis of motion on the corresponding side of the body in 
all parts below the section ; anaesthesia in all parts below the 
section, on the opposite side of the body ; and hypersesthesia 
in the parts below the section, upon the corresponding side 
of the body. 



SUMMARY-. OF THE SPIXAL CORD. 297 

The anatomical points bearing upon the physiological 
action of the cord are the following : 

The fibres from the anterior roots penetrate the anterior 
gray cornua directly and are in immediate connection with 
the prolongations of the motor cells. The motor cells also 
have prolongations which pass to the brain in the white sub- 
stance. The motor fibres are thus directly connected with 
the cellular elements of the cord, the elements probably con- 
cerned in reflex movements, and the cells are in connection 
with conducting fibres to the brain. 

The fibres from the posterior roots take several directions. 
Some of them pass to the gray substance. A portion passes 
to the posterior columns, some extending upward and others 
downward. The decussation, which is rendered certain by 
physiological experiments, has not been satisfactorily fol- 
lowed by anatomists. It undoubtedly takes place in the gray 
substance, probably in part by a crossing of the fibres them- 
selves, and in part by a crossing of prolongations from the 
cells with which certain fibres from the posterior roots are 
connected. 



CHAPTEE XI. 

. 

ACTION OF THE SPINAL COED AS A NEEVE-CEXTEE. 

Movements in decapitated animals Definition and applications of the term 
" reflex " Reflex action of the spinal cord History of the discovery of 
so-called reflex action Question of sensation and volition in frogs after 
decapitation Character of movements following irritation of the surface 
in decapitated animals Dispersion of impressions in the cord Conditions 
essential to the manifestation of reflex phenomena Exaggeration of reflex 
excitability by decapitation, poisoning with strychnine, etc. Reflex phe- 
nomena observed in the human subject. 

IT has long been known that decapitation of animals does 
not immediately arrest muscular action ; and the movements 
observed after this mutilation present a certain degree of 
regularity, and, of late years, have been shown to be in ac- 
cordance with well-defined laws. Under these conditions, 
the regulation of such movements is effected through the 
spinal cord and the nerves connected with it. If an animal be 
decapitated, leaving only the cord and its nerves, there is no 
sensation, for the parts capable of appreciating sensation are 
absent ; nor are there any true voluntary movements, as the 
organ of the will is destroyed. Still, in decapitated animals, 
the sensory nerves are for a time capable of conducting im- 
pressions, and the motor nerves can transmit a stimulus to 
the muscles ; but the only part capable of receiving an im- 
pression or of generating a motor stimulus is the gray matter 
of the cord. If, in addition to the Removal of all of the en- 
cephalic ganglia, the cord itself be destroyed, all movements 
of voluntary muscles are abolished, except as they may be 



THE SPESTAL COED AS A NEEVE-CEXTEE. 299 

produced by direct stimulation of the muscular tissue or of 
individual motor nerves. 

We must regard the gray matter of the brain and spinal 
cord as a connected chain of ganglia, capable of receiving 
impressions through the sensory nerves, and of generating 
the so-called nerve-force. The great cerebro-spinal axis, 
taken as a whole, has this general function ; but some parts 
have separate and distinct properties," and can act indepen- 
dently of the others. The cord, regarded as a conductor, 
connects the brain with the parts to which the spinal nerves 
are distributed. If the cord be separated from the brain in 
a living animal, it may act as a centre, independently of the 
brain ; but the encephalon has no communication with the 
parts supplied with nerves from the cord, and can only act 
upon the parts which receive nerves from the brain itself. 

It has been pretty clearly shown that when the cord is 
separated from the encephalon, an impression made upon 
the general sensory nerves is conveyed to its gray substance, 
and is transformed, as it were, into a stimulus, which is 
transmitted to the voluntary muscles, giving rise to certain 
movements, independently of sensation and volition. This 
impression is said to be reflected back from the cord through 
the motor nerves ; and the movements occurring under these 
conditions are called reflex. As they are movements excited 
by stimulation of sensory nerves, they are sometimes called 
excito-motor. 

The term reflex may properly be applied to any genera 
tion of nerve-force which occurs as a consequence of an im- 
pression received by a nerve-centre ; and reflex phenomena 
are by no means confined to the action of the spinal cord. 
The movements of the iris are reflex, and yet they take place 
in many instances without the intervention of the cord. 
The movements of respiration are reflex, and these are pre- 
sided over by the medulla oblongata. Movements of the 
intestines and the involuntary muscles generally are reflex, 
and they involve the action of the sympathetic system of 



300 NEKVOUS SYSTEM. 

nerves. Impressions made upon the nerves of special sense, 
as those of smell, sight, hearing, etc., give rise to certain 
trains of thought. These involve the action of the brain ; 
still they are reflex. In this last example of reflex action, it 
is sometimes difficult to connect the operations of the mind 
with external impressions as an exciting cause; but it is 
evident, from a little reflection, -that this is often the case. 
This fact is illustrated "by operations of the brain which take 
place, as it were, without consciousness, as in dreams. It 
has been clearly shown that a particular direction may be 
given to the thoughts during sleep, by impressions made 
upon the sense of hearing. A person sleeping may be made 
to dream of certain things, as a consequence of hearing pe- 
culiar noises. Examples of this kind of mental reflex action 
are sufficiently numerous and well authenticated. 1 

From the above considerations, it is evident that the 
term reflex may be properly used in connection with many 
phenomena involving the action of the sympathetic system 
and of the brain ; but it is generally understood as applying 
especially to involuntary movements, occurring without con- 
sciousness, as the result of impressions made upon the affe- 
rent nerves, and involving the independent action of the 
spinal cord. 

Reflex Action of the Spinal Cord. In 1832 and 1833, 
Marshall Hall described minutely the movements which take 
place in decapitated animals as a consequence of stimulation 
of the sensory nerves, and formularized these phenomena 
under the head of " the reflex function of the medulla ob- 
longata and medulla spinalis." a Since this publication, a 
new interest has been attached to the writings of some of 
the older physiologists, in which reflex action, as it is now 

1 For numerous instances of peculiar dreams referable to external impres- 
sions received during sleep, see, HAMMOND, Sleep and its Derangements, Philadel- 
phia, 1869, p. 12Y, et seq. 

2 MARSHALL HALL, On the Reflex Function of the Medulla Oblongata and Me' 
dulla Spinalis, London, 1833. 



EEFLEX ACTION OF THE SPINAL COED. 301 

understood, had been mentioned more or less definitely. In 
the history of important advances in physiological knowl- 
edge, it has often been the case that discoveries have been 
foreshadowed by the earlier writers ; and bibliographical re- 
search shows that the literature of the cord as a nerve-centre 
forms no exception to this, which is almost the rule. Some 
of the allusions to the cord as a centre of reflex action, 
made anterior to 1833, are vague and indefinite'; but, on 
the other hand, certain excito-motor actions were very ac- 
curately described, as early as 1812. Marshall Hall grouped 
and classified these phenomena, and showed their relations 
to the cord as an independent centre ; but, as we shall see, 
he has no claim to the title of the discoverer of reflex action, 
and his experiments presented little that was really new. 

AVhytt, in his work on the " Vital and other Involuntary 
Motions," states that the involuntary and mixed motions 
proceed from a stimulus, the latter being partly, and the 
former not at all, under the power of the will ; 1 and, by a 
stimulus, he means an impression made upon the sensory 
nerves. 

Prochaska, who wrote between 1778 and 179 7, states that 
the sensorium commune extends to the medulla spinalis, and 
that this " is manifest from the motions exhibited by decapi- 
tated animals, which cannot take place without the consen- 
tience and intervention of the nerves arising from the me- 
dulla spinalis ; for the decapitated frog, if pricked, not only 
withdraws the punctured part, but also creeps and leaps, 
which cannot be done without the consensus of the sensorial 
and motor nerves, the seat of which consensus must neces- 
sarily be in the medulla spinalis the remaining portion of 
the sensorium commune." a He calls this " reflexion," and 
speaks of it as taking place without consciousness, describing 
many phenomena now familiarly known as reflex. 

1 WHYTT, Works, Edinburgh, 1768, p. 170. 

8 PROCHASKA, A Dissertation on the Functions of the Nervous System, Syden- 
ham Society, London, 1851, p. 430. 



302 NERVOUS SYSTEM. 

Legallois published, in 1812, a remarkable memoir on 
the principle of life. In this work, he details numerous ex- 
periments, many of them on the nervous system, and of 
great interest in connection with the present question. In 
the rabbit, after division of the cord in the lumbar region, 
Legallois showed that " sensation and voluntary motion con- 
tinued to take place, even in the posterior extremities. But 
there is no longer any connection in sensation or movement 
between the anterior parts and the parts posterior to the 
section of the cord ; that is to say that, if the tail or, in- 
deed, one of the hind-feet be pinched, the entire posterior 
parts are agitated, but the anterior parts seem to feel noth- 
ing, and do not move." l 

Passing over a few confirmatory observations by other 
experimenters, we come to those of Fodera, in 1822. Fodera 
states that " in wounds of the spinal cord, the animal suffers 
pain and convulsions ; if it be divided transversely, there is 
paralysis of the posterior parts, w r ith loss of sensation and 
motion. But irritation applied below the section produces 
agitation of the muscles to which the nerves derived from it 
are distributed. The animal does not suffer pain, for it 
has no consciousness of what takes place in these parts." 2 
Again, Fodera says : " With regard to the spinal cord, com- 
plete transverse section in birds does not in general en- 
tirely paralyze the posterior extremities ; if we pinch the 
foot, they withdraw it, although they suffer no pain from it ; 
but if the spinal cord be entirely destroyed in the interior 
of the vertebral canal, the paralysis is perfect." ! At about 
the same time, Mayo described, even more definitely than 
his predecessors, the reflex function of the cord, in the fol- 
lowing words : 

1 LEGALLOIS, Experiences sur le prindpe de la vie. (Euvres, Paris, 1824, p. 80. 

2 FODERA, RecJierches experimentales sur le systeme nerveuz, Presentees d 
r Academic des sciences le 31 decembre, 1822. Journal de la physiologic ', Paris, 
1823, tome iii., p. 196. 

3 Op. tit., p. 214. 



REFLEX ACTION OF THE SPIXAL CORD. 303 

" On the one hand, it is clear that an influence, inde- 
pendent of the will, occasionally throws voluntary muscles 
into action, as appears in tetanus and other spasmodic dis- 
orders; and is shown remarkably in the physiological ex- 
periment of irritating the skin on the lower extremities, after 
the division of the spinal cord in the back, when the occur- 
rence of action limited to the muscles of the inferior extremi- 
ties, evinces that a connection exists, independently of the 
will, between sentient surfaces and the action of voluntary 
muscles. I have varied this experiment by dividing the 
spinal cord at once in the neck and in the back, upon which 
three unconnected nervous centres exist ; and the division 
of the skin of either part (and especially at the soles of the 
feet, in the two hinder portions) produces a convulsive action 
of the muscles of that part alone. The same influence may, 
then, possibly regulate the unconscious actions to which 
these remarks relate." 1 

The experiments of Marshall Hall, published in 1832 
and 1833, are familiar to every physiologist, as supplying 
nearly all of the omissions of the observers just cited. The 
points which he assumed to have experimentally demon- 
strated by his researches are as follows : A decapitated ani- 
mal, the only part of the cerebro-spinal axis which remains 
being the spinal cord, will make no movements, if complete- 
ly protected from all external impressions. An impression 
made upon the sensory nerves of a decapitated animal is 
reflected by the cord, through the motor nerves, to the mus- 
cles, and gives rise to reflex movements. If the cord be 
destroyed, no movements follow stimulation of the surface. 
If the centripetal and the centrifugal nerves be divided, no 
reflex movements can take place. Experiments upon de- 
capitated animals accord with the results of observations 
upon acephalous foetuses, and in cases of complete paraplegia 
from injury to the cord. All of the involuntary movements 

1 MAYO, Anatomical and Physiological Commentaries, Number II., July, 1823, 
London, 1823, p. 17. 
120 



304 NEKVOUS SYSTEM. 

observed in the healthy body are explained by the theory of 
reflex action. 1 These observations of Marshall Hall were, in 
the main, confirmed by Miiller, the year succeeding their 
first publication ; 3 and, by some writers, the credit of the 
discovery of the mechanism of reflex action is given to both 
Miiller and Marshall Hall. 

From the point of view which the present condition of 
science enables us to take with regard to the reflex action 
of the cord, we have to determine the accuracy of the obser- 
vations of Marshall Hall, and to follow out the advances 
that have been made by more recent observers. It is impor- 
tant, as the first step in our inquiry, to ascertain the exact 
condition of decapitated animals as regards their capacity 
for muscular movements ; and upon this point there is some 
difference of opinion. Marshall Hall thought that an ani- 
mal, a frog, for example, after decapitation, was incapable 
of any voluntary movement, or of any movement which did 
not have, for its exciting cause, an external impression. "We 
take the example of frogs, because these are the animals 
most commonly used by experimenters. 

All who have experimented upon frogs have seen them 
jump about vigorously after decapitation ; and the question 
whether these be spontaneous movements, so called, or an 
excito-motor action, is more difficult to determine than 
would at first sight appear. It would be unphilosophic to 
assume that because the animal has been decapitated, the 
movements are due to external impressions only, if we use 
this as evidence against the possibility of spontaneous 
movements under these conditions. The obvious necessity 
of the argument is to remove all possibility of external im- 
pressions, or of irritation of the cord itself. Upon this 

1 MARSHALL HALL, Reflex Function of the Medulla Oblongata and Medulla 
Spinalis, London, 1833 ; and, Memoirs on the Nervous System, London, 1837. 
Marshall Hall states that his first publication appeared in the Proceedings of 
the Zoological Society, in 1812. 

2 MULLER, Elements of Physiology, translated by Baly, London, 1840, pp. 761, 
J99.* The first edition of M tiller's work was published in Berlin, in 1833. 



REFLEX ACTION OF THE SPINAL COED. 305 

point we can only speak positively from our own experiments. 
If a frog be decapitated, so as to leave only the spinal cord 
intact, if we wait for from one to three minutes until the 
effects of the shock and local irritation have subsided, if we 
then, when the animal has become perfectly quiet, cover it 
with a bell-glass, and finally, if we remove all possibility of 
jarring the table on which the animal is placed, there is no 
movement of muscles. In making an experiment of this 
kind, we occasionally see movements which are due to a 
very feeble impression, such as a breath of air, or a jar from 
the street, but which is perfectly evident to the observer ; 
and, when a movement is once made, this gives rise to an- 
other impression, and thus, successive actions of the muscles 
may take place. The movements in jumping are so simple 
that they seem, sometimes, under these conditions, to be vol- 
untary. The effect of feeble excitations is also very marked 
in animals poisoned with strychnine ; but, even here, we do 
not have movements, unless an impression be first made 
upon the sensory nerves. When we come to experiments 
upon the mammalia, there can hardly be any question of this 
kind ; for here, as the rule, no movements are observed after 
the encephalic ganglia have been removed, unless the sen- 
sory nerves be pretty strongly stimulated. Analogous phe- 
nomena are observed in the lower extremities, in cases of 
paraplegia in the human subject. 

The next important question to determine is with regard 
to the nature of movements excited by external stimulation 
in decapitated animals, especially frogs ; for some of these 
movements are so regular as to appear to be connected with 
sensation and volition. The experiments of Pfliiger upon 
this point are very remarkable. These have been repeatedly 
confirmed, and there can be no doubt with regard to their 
accuracy. Pfiiiger carefully removed from a frog the entire 
encephalon, leaving only the spinal cord. He then touched 
the surface of the thigh over the inner condyle with acetic 
acid, to the irritation of which frogs are peculiarly sensitive. 



306 NEBVOUS SYSTEM. 

The animal thereupon rubbed the irritated surface with the 
foot of the same side, apparently appreciating the locality of 
the irritation, and endeavoring, by a voluntary effort, to re- 
move it. The foot of this side was then amputated, and 
the irritation was renewed in the same place. The animal 
made an ineffectual effort to reach the spot with the ampu- 
tated member, and, failing in this, after some general move- 
ments of the limbs, rubbed the spot with the foot of the 
opposite side. 1 Although this experiment does not always 
progress precisely in the manner described, it has succeeded 
perfectly in so many instances as to lead some physiologists 
to conclude that sensation and volition are not entirely abol- 
ished by removal of the encephalon, at least in frogs. 2 

The remarkable phenomena just detailed are to be re- 
garded from two points of view : first, with reference to 
their bearing upon the question of the existence of percep- 
tion and volition in the spinal cord of the frog ; and second, 
the question of the application of these phenomena to the 
physiology of the cord in man and the higher classes of ani- 
mals. The conditions of the experiment in the frog are sim- 
ply these : Instead of exposing the surface to a single and 
instantaneous stimulation, the excito-motor effects of which 
are observed as a direct response to the irritation, and im- 
mediately cease, we have, by the application of acetic acid 
to the surface, a prolonged impression upon the sensory 
nerves, which, by virtue of the anatomical connections be- 
tween the different parts of the cord, is proba'bly dispersed 
throughout the entire spinal axis. That powerful impres- 

1 PFLUGER, Die sensorischen Functionen des RuclcenmarTcs der Wirbelthiere, 
Berlin, 1853, S. 124," et seq. 

2 Observations of very much the same character as those of Pfliiger were 
published by Patqn, in 1858. He refers to experiments showing the perceptive 
power of the cord, by Dr. Dowler, of New Orleans, but does not allude to the 
experiments of Pfliiger. (PATON, On the Perceptive Power of the Spinal Cord 
as manifested by Experiments on Cold-blooded Animals. North American Medico- 
Chirurgical Review, Philadelphia, 1858, vol. ii., pp. 467, 703). These obser- 
rations have been repeatedly confirmed by other physiologists. 



REFLEX ACTION OF THE SPINAL CORD. 307 

Bions may be thus dispersed, there can be no doubt, as we 
shall see farther on. The phenomena under consideration 
certainly point to an appreciation by the cord of the locality 
of a powerful impression, and this could be manifested in an 
animal only by an apparent muscular effort to reach the irri- 
tated spot ; but we can hardly reason from this fact, that in 
man and the higher animals, the spinal cord shares with the 
brain the power of appreciating what we know as sensation 
and of generating the stimulus of true voluntary movement. 
If a sudden and very powerful painful impression be made 
upon the surface in man under normal conditions, the hand 
may be instantly applied to the affected part, apparently be- 
fore we really appreciate the pain or have time to make a 
distinct effort of the will ; but the connections between the 
different parts of the cerebro-spinal axis do not permit us to 
isolate the action of the cord. Certain it is that, in the higher 
animals, after removal of the encephalon, and in experiments 
upon decapitated criminals and patients suffering from para- 
plegia, there is no evidence of true sensation or volition in 
the spinal cord ; and in man and the higher animals, we 
must regard all muscular movements which depend solely 
upon the action of the cord as a nerve-centre as automatic 
and entirely independent of consciousness and of the will. 

It is easy to determine, by experiments to which we have 
already incidentally alluded, that the muscular movements 
dependent upon nervous action, occurring in decapitated 
animals, are due to the action of the spinal cord as a nerve- 
centre. In an animal in which the reflex phenomena are 
very marked, as they are after decapitation, especially if the 
animal be poisoned with strychnine or opium, all movements 
cease immediately when the cord is destroyed. That the 
gray matter of the cord is the part concerned as a centre in 
the production of these phenomena, is probable, in view of 
what we know with regard to the general functions and 
properties of this substance ; and experiments have shown 
that this is the fact. If, in a decapitated frog, we make a 



308 NERVOUS SYSTEM. 

longitudinal section of the cord in the median line, leaving 
only a slight communication between the two sides, we may 
sometimes succeed, by strongly irritating the skin of one leg. 
in producing reflex movements, not only in the same leg, 
but in the leg of the opposite side ; and it is reasonable to 
suppose that the irritation is propagated from one side to 
the other through the cells of the gray matter. 1 

The conditions essential to the manifestations of reflex 
phenomena depending upon the action of the cord are very 
simple and easily understood. 

In the first place, it is necessary that one or more of the 
posterior roots of the spinal nerves should be in communica- 
tion with the cord, in order to conduct the impression to this 
nerve-centre. If all of the posterior roots be divided, there 
is no nervous communication between the periphery and the 
centre, and no movements follow irritation of the surface. 
When the excitability of the cord is exaggerated, as in poi- 
soning by strychnine, a single posterior root is sufficient to 
conduct an impression to the cord, which will give rise to 
violent contractions of all the muscles. 2 This is due to a dis- 
persion of the impression, under these conditions of increased 
excitability, from the single point of entrance of the poste- 
rior root, throughout the cord. In animals that have been 
simply decapitated, a similar dispersion of impressions may 
also take place. If a comparatively feeble single impression 
be made upon any part of the general surface, as the rule, 
the subjacent muscles only are the seat of contraction ; but 
if the impression "be more powerful, or if it be prolonged, as 
when we apply a drop of acetic acid to any part of the skin 
of a frog, this impression may be diffused throughout the 
cord, producing contractions of the general muscular system. 
We have already shown, in treating of the general properties 
of the sensory nerves, that an impression made at any point 
in the course of a nerve is conducted to the centre. Reflex 

1 LONGET, Traiti de physiologie, Paris, 1869, tome Hi., p. 260. 
* BERNARD, Systeme nerveux, Paris, 1858, tome i., p. 342. 



BEFLEX ACTION OF THE SPINAL CORD. 309 

movements may, consequently, be produced by stimulating 
the sensory nerves in their course, or by irritating the poste- 
rior roots of the spinal nerves. 

TTe have already stated that the cord must retain its 
anatomical integrity, in order to receive an impression made 
upon the centripetal nerves, and transform it, as it were, into 
a stimulus, which is reflected back by the motor nerves and 
produces muscular contraction. It is also evident ' that the 
motor nerves must retain their connection with the cord, 
and be in a condition to conduct the stimulus reflected by 
the cord to the muscles. 

The reflex excitability of the spinal cord is increased to 
a marked degree by separating this portion of the cerebro- 
spinal axis from the encephalon, and the same is true for the 
lower portion of the cord, when a section is made in the dor- 
sal or the lumbar region. It is difficult to find an entirely 
satisfactory explanation of this fact ; and the phenomena ob- 
served under these conditions are, in this regard, like the 
exaggerated sensibility of portions of the general surface 
after section of certain columns of the cord. Setschenow 
proposed, some years ago, the theory that the reflex excita- 
bility of the cord under natural conditions was subject to a 
moderating, or an inhibitory influence from the encepha- 
lon ; and that this influence being absent in decapitated ani- 
mals, the excitability of the cord, under these conditions, 
seemed to be exaggerated. 1 Whether this explanation be 
accepted or not, the fact remains, that reflex phenomena 
are more easily excited and are more marked in animals 
after decapitation, than in the same animals, when the con- 
nections between the cord and brain have not been de- 
stroyed. In addition, Yulpian has shown that the excita- 
bility is intense in proportion as the part of the cord con- 

1 SETSCHENOW, Physiologische Studien uber die Hemmungsmechanismen fur 
die Rfflexthatigkeit des Ruckenmarks im Gehirne des Frosches, Berlin, 1863 ; and, 
SETSCHENOW UND PASCHTTTIN, Neue Versuche am Him und Riickenmark, Berlin, 
1865. 



310 NERVOUS SYSTEM. 

cerned in the reflex phenomena is restricted; and, after 
section of the cord itself, the most powerful and easily-ex 
cited movements are produced when the division has been 
made low down in the lumbar region. He has also shown 
that simple puncture of the cord produces an exaggeration 
of the reflex excitability, as well as hyperaesthesia. 1 

In experiments upon animals, the reflex phenomena are 
greatly exaggerated in intensity in the tetanic condition pro- 
duced by poisoning by opium or strychnine. Take, for 
example, a frog decapitated and poisoned with strychnine. 
No reflex movements occur unless an impression be made 
upon the sensory nerves; but the faintest irritation, such as 
a breath of air or a slight jar, throws the entire muscular 
system into a condition of violent tetanic spasm. The same 
phenomena are observed in cases of poisoning by strychnine, 
or of tetanus, in the human subject. This fact is important 
in its relations to the treatment of these conditions ; for it 
is evident that, in such cases, the exhaustion due to the vio- 
lent spasms may be moderated by carefully avoiding all un- 
necessary irritation of the surface. 

It was shown a number of years ago, by Longet, that the 
inhalation of anaesthetic agents may abolish all of the ordi- 
nary reflex phenomena. 2 "Whether this be due to an action 
upon the cord itself or to a paralysis of the sensory nerves, 
it is difficult to determine. Ordinarily, in animals rendered 
insensible by anaesthetics, the reflex act of respiration con- 
tinues ; but this may also be arrested, as has been observed 
by all who have experimented with anaesthetics, especially 
w T ith chloroform. A common way of determining that an 
animal is completely under the influence of ether is by an 
absence of the reflex act of closing the eyelids when the 
cornea is touched. 

It now only remains to show that the phenomena of re- 
flex action observed in experiments upon the inferior ani- 

1 VULPIAN, Systeme nerveux, Paris, 1866, pp. 441, 442. 

2 LONGET, Traite de physiologie, Paris, 1869, tome iii., p. 256. 



REFLEX ACTION OF THE SPINAL COED. 311 

mals, especially frogs, are applicable to the human subject, 
and to indicate the muscular actions which depend upon the 
cord as a nerve-centre. 

It is only necessary, after what has gone before, to indi- 
cate in a general way the phenomena observed in the human 
subject which illustrate the reflex action of the cord. It is a 
common observation, in cases of paraplegia in which the 
lower portion of the cord is intact, that movements of the 
limbs follow titillation of the soles of the feet, these move- 
ments taking place independently of the consciousness or the 
will of the subject experimented upon. Acephalous foetuses 
will present reflex movements, movements of respiration, 
and will even suck when the finger is introduced into the 
mouth. Observations of this kind are so numerous and fa- 
miliar, that they need not be cited in detail. Experiments 
have also been made upon criminals after decapitation ; and 
although the reflex phenomena are not so well marked and 
cannot be excited so long after death as in cold-blooded ani- 
mals, they are sufficiently distinct. In 1869, quite an elab- 
orate series of investigations of this kind was made by Ro- 
bin. 1 

It is difficult, in studying, in the human subject, the ordi- 
nary phenomena of movements in the voluntary muscular 
system, to isolate the reflex phenomena from those acts in- 
volving sensation and volition. In many persons, titillation 
of the soles of the feet produces violent contractions of 
muscles, which cannot be arrested by an effort of the will, 
and this may even be followed by general convulsions. 
When we unexpectedly touch an irritating surface with the 
hand, the muscles of the arm act so quickly, that we may 
suppose that this takes place before we really appreciate the 
painful sensation ; and, if the impression be very severe, we 
may have movements more or less general. Operating upon 
highly-sensitive parts, it is frequently impossible to arrest re- 

1 ROBIN, Observations anatomiques et physiologiques faites sur des suppli- 
cies par decollation, Journal de Vanatomie^ Paris, 1869, tome vi., p. 69, et seq. 



312 NERVOUS SYSTEM. 

flex movements, as the closing of the eyelids when the cor 
nea is touched. True reflex movements may be produced 
by carefully-executed experiments upon persons asleep. 
We cannot arrest the act of vomiting induced by titillation 
of the fauces ; and other instances of this kind might be 
cited. 

Most of the true involuntary movements are reflex ; but 
these have been or will be considered under their proper 
heads. The movements of deglutition depend upon an im- 
pression made upon the mucous membrane of the pharynx, 
etc. The movements of respiration are excited by an impres- 
sion made upon the general sensory nerves, due to want of 
oxygen, as we have shown in treating of respiration. The 
ejaculation of semen is also reflex. Important reflex actions 
take place through the sympathetic nerves, such as the 
movements of the intestines, vaso-motor movements, etc. ; 
but these will be considered fully under the head of the 
sympathetic system. Secretion, the action of the heart, 
the contractions of the uterus, the action of the sphincters, 
the movements of the iris, etc., take place through the sym- 
pathetic and the cerebro-spinal system. 

As regards the farther action of the cord as a nerve-centre, 
there are undoubtedly many functions influenced more or 
less by this portion of the cerebro-spinal axis ; but these have 
been treated of under their appropriate heads, or will be con- 
sidered hereafter. 



CHAPTER XII. 

THE CEREBRAL HEMISPHERES. 

Pbysiological divisions of the encephalon Weight of different parts of the 
brain and of the entire encephalon Some points in the physiological anat- 
omy of the encephalon and its connections The cerebrum General prop- 
erties of the cerebrum Functions of the cerebrum Extirpation of the 
cerebrum in animals Pathological facts bearing upon the functions of 
the cerebrum Comparative development of the cerebrum in the lower 
animals Development of the cerebrum in different races of men and in 
different individuals Ethnological table, derived from autopsies of white 
and negro brains Table of weights of the encephalon in different indi- 
viduals Location of the faculty of articulate language in a restricted por- 
tion of the anterior cerebral lobes. 

THE anatomy of the encephalon is so complex, that it can 
be treated of with advantage only by a very minute and care- 
fully-illustrated description, such as is to be found in some 
of the elaborate anatomical works or in special treatises on 
the nervous system. We shall not consider under a distinct 
head the general physiological anatomy of the brain, for the 
reason just given, and also because we are as yet ignorant 
of the exact connection between the structure and arrange- 
ment of many of its parts and their physiology. "We know 
that the gray substance is capable of appreciating general 
and special impressions received by the peripheral nervous 
system, and of generating the so-called nerve-force. Impres- 
sions are conveyed to this portion of the cerebro-spinal axis 
by the sensory conductors, passing to the brain, either through 
the cord or by the cranial nerves, and by the nerves of special 
sense, as well as those of general sensibility. The stimulus 



314 NERVOUS SYSTEM. 

wliicli gives rise to voluntary movements is generated in the 
brain, and is conveyed by the motor nerves to the appro- 
priate muscles. We have seen, also, that the centres of the 
encephalon may be concerned in reflex action. In addition, 
parts of the brain act as centres of sensation and volition and 
are concerned in the varied phenomena of intellection. 

The encephalon, or what is ordinarily known as the brain, 
consists of a number of ganglia, or collections of gray matter, 
connected with each other, and also, by the different columns 
of the cord, with the motor and sensory nerves of the gen- 
eral system. Certain of these ganglia have separate and dis- 
tinct functions, which are more or less completely understood ; 
while there are, in addition, masses of gray substance, the 
physiological relations of which are as yet obscure or entirely 
unknown. The greatest and the most important of all, the 
gray matter of the cerebral hemispheres, undoubtedly has 
subdivisions connected with distinct attributes of the mind ; 
but our positive knowledge with regard to these divisions is, 
at the present day, very meagre, though this subject has long 
been a favorite field for philosophic speculation. 

Confining ourselves strictly to the limits of positive infor- 
mation, we may recognize the following parts of the encepha- 
lon as distinct ganglia : 1. The gray matter of the cerebral 
hemispheres ; 2. The gray matter of the cerebellum ; 3. The 
olfactory ganglia ; 4. The gray matter of the corpora striata ; 
5. The gray matter of the optic thalami ; 6. The tubercula 
quadrigemina ; 7. The gray matter of the tuber annulare, or 
pons Yarolii ; 8. The ganglion of the medulla oblongata. In 
addition, the following parts have been made the subject of 
physiological investigation or speculation, with results more or 
less definite. The peduncles of the cerebrum and of the cere- 
bellum ; the pineal gland ; the corpus callosum ; the septum 
lucidum ; the cerebral ventricles ; and the pituitary body. 
"We have, however, little if any positive information concern- 
ing these parts, except their general anatomical relations ; 
and their physiology really amounts to little more than a 



THE CEREBRAL HEMISPHERES. 315 

history of the vague speculations of the ancients or the fruit- 
less experiments of modern observers. It is to be hoped that 
future anatomical investigations, chiefly in following out 
the course of the fibres of the encephalon and their connec- 
tions with the cells of the different collections of gray mat- 
ter, will throw light upon the functions of this part of the 
cerebro-spinal axis; but at present, all physiologists will 
admit that we have received very little aid from this 
source. In our anatomical descriptions, therefore, we shall 
confine ourselves to those points that are strictly physio- 
logical. 

Weight of different Parts of the Brain and of the entire 
Encephalon. Most of the tables of the weight of the healthy 
adult brain of the Caucasian, given by different observers, 
show essentially the same results, the differences amounting 
to only one or two ounces for the entire encephalon. The 
average given by Quain is 49J ounces, avoirdupois, for the 
male, and 44 ounces for the female. This is the general re- 
sult obtained by combining the tables published by Sims, 
Clendinning, Tiedemann, and Reid. The number of male 
brains weighed was 278, and of female brains, 191. In 
males, the minimum weight was 34: ounces, and the maxi- 
mum, 65 ounces. In 170 cases but of the 278, the weight 
ranged from 46 to 53 ounces, which may be taken as the 
general average. In females, the minimum was 31 ounces, 
and the maximum, 56 ounces. In 125 cases out of the 191, 
the weight ranged from 4:1 to 47 ounces. 

Quain assumes, from various researches,, that in new- 
born infants, the brain weighs 11 '65 ounces, for the male, 
and 10 ounces, for the female. In both sexes, " the weight 
of the brain generally increases rapidly up to the seventh 
year, then more slowly to between sixteen and twenty, and 
again more slowly to between thirty-one and forty, at which 
time it reaches its maximum point. Beyond that period, 
there appears a slow, but progressive diminution in weight 



316 NERVOUS SYSTEM. 

of about one ounce during each subsequent decennial period ; 
thus confirming the opinion, that the brain diminishes in ad- 
vanced life." 

The comparative weights of the several parts of the en- 
cephalon, calculated from observations on the brains of fifty- 
three males and thirty-four females, between the ages of 
twenty-five and fifty-five, are as follows : 





Males. 


Females. 


Average weight of cerebrum 


43'98 oz. 


38'75 oz. 




5-25 " 


4'76 " 


Average weight of pons and medulla oblon^ata 


0-98 " 


roi " 








Average weight of entire encephalon 


50-21 oz 


44-52 oz. 









The proportionate weight of the cerebellum to that of 
the cerebrum, in the male, is as 1 to 8f, and in the female, 
as 1 to 8J. 

The specific gravity of the whole encephalon is about 
1,036, that of the gray matter being 1,034, and of the white, 
1,040.' 

The above weights are quoted from Quain's admirable 
work on anatomy, and the normal range of variations and 
averages only are given. "When we come to treat of the 
cerebrum and its relations to intelligence, we will discuss 
the weights of the brain in idiots and in persons of extraor- 
dinary intellectual power, as far as any data upon these 
points are to be found. 



Some Points in the Physiological Anatomy of the 
cephalon and its Connections. The direction of the fibres 
in the encephalon, their connections with the cells of the 
gray substance, the course of commissural fibres connecting 
together the different parts of the gray substance of the cere- 
brum, the cerebellum, and the deeper ganglia, and finally 
the avenues of communication between the fibres of the en- 
cephalon and the cord, are points of exceeding intricacy ; 

1 QUAIN, Elements of Anatomy, London, 1867, vol. ii., p. 568, et seq. 



THE CEREBRAL HEMISPHERES. 317 

and many of them are still so uncertain and obscure, that 
they cannot as yet be connected satisfactorily with the exact 
results of physiological inquiry. All that we can do at pres- 
ent, is to recognize certain ganglionic masses, the separate 
functions of which have been more or less accurately de- 
nned, and show, as far as possible, their anatomical relations 
to each other and to the cord. 

The separate collections of gray matter concerning which 
we possess positive physiological knowledge are, the gray 
matter of the cerebral hemispheres and of the cerebellum, 
the corpora striata, optic thalami, tuber annulare, or pons, 
and the medulla oblongata. To these may be added, the 
olfactory ganglia, which preside over the sense of smell, and 
the tubercula quadrigemina, or optic lobes, which are the 
centres connected with vision. The minute anatomy of the 
nerve-fibres and the nerve-cells, with their mode of connec- 
tion with each other, have been already considered with suf- 
ficient minuteness under the head of the general structure 
of the nervous system. 1 We shall here discuss chiefly the 
direction of the fibres through which the encephalic ganglia 
are connected with the periphery, the fibres connecting the 
different ganglia with each other, and, in the case of the 
larger ganglia, certain commissural fibres connecting to- 
gether their different parts. 

In the wealth of literature pertaining to the minute 
anatomy of the encephalon, it is somewhat difficult to sepa- 
rate and define the well-established facts which have a direct 
bearing upon physiology. Perhaps the most elaborate and, 
to a certain extent, the most satisfactory observations upon 
the various points to be considered, are those of Luys ; but 
this author describes the course of the fibres with an exacti- 
tude that seems hardly justified, in all instances, by the facts, 
in view of the inevitable difficulty and uncertainty of some 
of the processes employed ; and the graphic and admirable 
delineations by which the work is illustrated, though profess- 

1 See Chapter I. 



318 NERVOUS SYSTEM. 

edly schematic, present a degree of ideality which inspires 
some distrust with regard to the accuracy of the general 
conclusions. 1 According to Luys, the fibres of the encepha- 
lon have several directions, as follows : 

The gray matter of the cerebral hemispheres, as we shall 
see farther on, is composed of a mass of nerve-cells, con- 
nected together by their prolongations into a plexus, which, 
in its turn, is connected with the fibres of the white sub- 
stance. 

From this cortical cellular plexus, white fibres arise, 
which may be divided, according to their direction and des- 
tination, into two classes : The first class consists of curved 
commissural fibres, which pass into the white substance to a 
certain depth and return to the gray matter, connecting thus 
the gray substance of adjacent convolutions. The existence 
of these fibres and their direction are well established. The 
second class consists of fibres which, arising from the gray 
substance of the convolutions, connect these with the cor- 
pora striata and the optic thalami. These may bo called the 
converging fibres ; and their general direction, as far as it 
has been ascertained, is as follows : 

Arising from the internal, concave surface of the corti- 
cal substance of the cerebrum, the converging fibres, at first 
running side by side with the curved commissural fibres, 
separate from the latter as they curve backward to pass 
again to the cortical substance, and are directed toward the 
corpora striata and the optic thalami. The limits of the 
irregular planes of separation of the commissural and the 
converging fibres contribute to form the boundaries of the 
ventricular cavities of the brain. If we study the course of 
the converging fibres arising from all points in the concave 
surface of the cerebral gray matter, we find that they take 
various directions. The fibres from the anterior region of 
the cerebrum pass backward, and form distinct fasciculi 

1 LUYS, Recherches sur le systeme ntrvrux cerebro-spinal, sa sti-ucfure, ses /one- 
tions tt ses maladies, Paris, 1865. 



THE CEREBRAL HEMISPHERES. 319 

which converge to the gray substance of the corpora otriata. 
The fibres from the middle portion converge regularly to the 
middle region of the external portions of the optic thalami. 
The fibres from the posterior portion pass from behind for- 
ward, and distribute themselves in the posterior portion of 
the optic thalami. The fibres from the convolutions of the 
hippocampi and the fascia dentata are lost in the gray sub- 
stance lining the internal borders of the optic thalami. In 
addition to these converging fibres and the curved commis- 
sural fibres connecting the different convolutions of each 
hemisphere with each other, are commissural fibres which 
connect the two hemispheres, as well as fibres connecting 
together the corpora striata and the optic thalami of the 
two sides. 

Certain of the fibres converging from the gray substance 
of the hemispheres to the corpora striata and optic thalami 
are probably connected with the cells in the gray matter of 
these parts. Other fibres pass through the corpora striata 
and optic thalami to become finally connected with the 
fibres of the medulla oblongata, and, through the medulla 
pblongata, with the columns of the spinal cord. Following 
the antero-lateral columns of the cord from below upward, 
they ascend to the medulla oblongata, decussate in the me- 
dian line, and from the medulla pass to the brain. Certain 
of these ascending fibres, which are nearly all continuations 
of the antero-lateral columns of the cord, ascend to the brain 
by passing deeply through the pons Yarolii ; other fibres as- 
cend in the cerebral peduncles, or crura cerebri ; and other 
fibres pass to the tubercula quadrigemina. As the bundles 
of fibres ascend from the medulla oblongata, they become 
more and more numerous by reinforcements of fibres, proba- 
bly derived from the cells of the collections of gray matter in 
their course. 

"We have attempted, in the above sketch of the fibres of 
the brain, to give a succinct account of the points that are 
most interesting from their physiological relations, and to' 

121 



320 NEKVOUS SYSTEM. 

confine our description, as far as possible, to anatomical facts 
that have been definitively settled and are now generally ac- 
cepted. But, as we have before remarked, the course of the 
fibres and their connections are so exceedingly intricate, that 
we cannot rely entirely upon purely anatomical investiga- 
tions. The results obtained by anatomists should be con- 
trolled, as far as possible, by physiological and pathological 
observations. When anatomical researches are directly op- 
posed to the conclusions to be deduced from experiments 
upon living animals, in view of the great uncertainty of the 
former, it will generally be reasonable to assume that they 
are erroneous or incomplete. We know, as the results of 
experiments on animals, that the motor stimulus is con- 
ducted from the brain by the antero-lateral columns of the 
cord, and that the conducting fibres decussate at the medulla 
oblongata. This fact has been verified by pathological ob- 
servations, chiefly in cases of injury to the brain-substance 
from haemorrhage, softening, etc. We know that impres- 
sions are appreciated as sensations in some part of the cere- 
brum, and that the sensory conductors also decussate ; as is 
shown by occasional paralysis of both motion and sensation 
following brain-lesions. It is evident, therefore, that sensory 
conductors pass to the brain, but their precise course is not 
easy to determine. We have seen, in treating of the action 
of the cord as a conductor, that sensory impressions are 
transmitted by the gray substance alone, and it is probably 
through connections between the cells of the different cen- 
tres that these impressions are finally carried to the brain. 
The physiological fact of the conduction of sensory impres- 
sions is fully confirmed by pathology, but its mechanism has 
been very little, if at all, elucidated by anatomical re- 
searches. 

We have left certain anatomical points relating to the 
cerebrum, cerebellum, tiiber annulare, and medulla oblon- 
gata, to be described separately in connection with these 
'divisions of the encephalon. 



THE CEREBRUM. 321 

The Cerebrum. 

The anatomical description which we have just given of 
the encephalon will answer for most of the points of physio- 
logical interest connected with the cerebrum. As we have 
seen, the cerebrum constitutes more than four-fifths of the 
encephalic mass. Its gray matter, which is external and 
follows the convolutions, is from -^ to -J- of an inch in thick- 
ness. 1 Writers have described this substance as existing in 
several layers, but this division is mainly artificial. In cer- 
tain parts, however, particularly in the posterior portion of 
the cerebrum, the gray substance is quite distinctly divided 
into two layers, by a very delicate intermediate layer of a 
whitish color. 

There is a marked difference in the appearance of the 
cells in the most superficial and in the deepest portions of 
the gray substance. The superficial cells are small, and 
present a net-work of delicate, anastomosing fibres, re- 
sembling the cells of the posterior cornua of the gray 
substance of the cord ; while the deepest cells are large, and 
resemble the so-called motor cells of the cord. Between 
these two extremes, in the intermediate layers, there is a 
gradual transition in the size of the cells.' This anatomical 
fact points to the possibility of distinct functions of the cells 
belonging to the superficial and the deep layers ; viz., that 
the larger cells are for the generation of the motor stimulus, 
while the smaller are for the reception of sensory impres- 
sions. This, however, is mere supposition, incapable, as 
yet, of positive demonstration. 

1 LUYS, Systeme nerveux, Paris, 1865, p. 161. 

2 The above general description of the peculiarities of the nerve-cells of the 
cerebral convolutions is the one given by most anatomists. Lately, Lockhart 
Clark has described the structure of the convolutions very minutely, dividing 
the gray substance into seven distinct layers. This description is interesting, 
but chiefly so from an anatomical point of view. (LOCKHART CLARK, The 
Structure of the Cerebral Convolutions. Quarterly Journal of Psychological 
Medicine, Xew York, 1869, vol. in., p. 517.) 



322 NERVOUS SYSTEM. 

The mode of connection between the cellular and the 
fibrous elements of the nervous system has .already been 
considered, and does not demand further mention. 1 We 
will also pass over the amorphous matter, nuclei, myelo- 
cytes, etc., found in the central nervous matter, as these 
points possess little or no physiological interest. 

General Properties of the Cerebrum. By the general 
properties of the cerebrum, we mean the effect, or the ab- 
sence of effect, observed when the gray or white substance 
is subjected to direct irritation. While some of the older 
writers state that the brain is both irritable and sensible, 2 
nearly all authorities, up to a very recent date, are agreed 
that direct stimulation of the white or the gray substance of 
the greatest part of the brain produces neither pain nor 
convulsive movements. Among the numerous experimenters 
who have exposed the brain and noted the absence of pain 
and convulsions after direct stimulation of both the gray 
and the white matter, may be mentioned Flourens, 3 Ma- 
gendie, 4 and Longet. Longet states that he has exposed the 
cerebrum in goats, and irritated both the white and the gray 
substance by laceration, cauterization with potash and nitric 
acid, the galvanic current, etc., with purely negative results. 6 
In numerous experiments upon pigeons, we have invariably 
observed the same insensibility and inexcitability of both 
the gray and the white substance of the cerebral hemi- 
spheres. 

1 See page 60. 

2 The most definite experiments on this point are those made by Haller and 
Zinn, these observers noting, as it seemed to them, indications of pain, and 
convulsive movements, immediately following mechanical irritation of the brain. 
(HALLER, Memoir -es sur la nature sensible et irritable des parties du corps animal^ 
Lausanne, 1756, p. 201, et seq.) 

8 FLOURENS, Systeme nerveux, Paris, 1842, p. 18. 

4 MAGENDIE, Lemons sur les fonctions et les maladies du systeme nerveux, Paris, 
1841, tome i., p. 175, et seq. 

6 LONGET, Anatomic et physiologic du systeme nerveux, Paris, 1842, tome i., 
pp. 642, 644. 



GENERAL PROPERTIES OF THE CEREBRUM. 323 

From the above facts, all physiologists of the present day 
are agreed that a great part of the substance of the cerebrum 
is neither excitable nor sensible, in the sense in which these 
terms are applied to the ordinary mixed nerves. There can 
be no doubt with regard to the conducting properties of the 
white matter of the brain, but the nerve-fibres here seem to 
conduct impressions conveyed to them by the sensory nerves 
and the stimulus generated by the nerve-cells, without being 
capable of receiving or conducting artificial impressions ap- 
plied directly to their substance. 

We have said that a great part of the cerebral substance 
seems to be neither excitable nor sensible to direct stimula- 
tion ; but we must make an exception in favor of certain 
portions of the cerebrum, which have lately been shown to 
possess excitability, their action being confined to particular 
sets of muscles. Fritsch and Hitzig, exposing the cere- 
bral hemispheres in dogs, found that certain parts of its an- 
terior portion responded to a feeble galvanic current. The 
stimulation was applied by means of two needles, conducting 
a feeble galvanic current, introduced through the gray into the 
white substance. Each galvanization produced movements 
restricted to particular sets of muscles ; but it was difficult to 
say whether the contractions were due to stimulation of the 
white or of the gray substance. Different centres for the 
sets of muscles were accurately determined. The centre for" 
the muscles of the neck was located in the middle of the 
frontal convolution ; external to that,* was a centre for the 
extensor and adductor muscles of the forelegs ; and so on, 
other centres for sets of muscles being found in the anterior 
portion of the hemispheres. By passing an interrupted cur- 
rent through these parts, tetanus of particular muscles was 
produced. In. other observations, when the gray substance 
was removed at the points mentioned, there was partial loss 
of power, but not paralysis, of the sets of muscles correspond- 
ing to the centres operated upon. The authors regarded 
this as due to a loss of " muscular sense." In these experi- 



324 NERVOUS SYSTEM. 

ments, the action was always crossed. It was also found that, 
after severe haemorrhage, the excitability of the cerebrum 
quickly disappeared, which may account for the negative re- 
sults obtained by previous experimenters. ~No motor prop- 
erties were found in the posterior portion of the cerebrum. 1 

The experiments just cited throw a new light upon the 
properties of the cerebral substance. It has always been found 
difficult to experiment upon the great encephalic centres 
without disturbing the physiological conditions so seriously 
as to render the results of direct observations of this kind 
more or less indefinite. Now that it is ascertained that, in 
all probability, these centres readily lose their normal prop- 
erties as a simple consequence of haemorrhage and exposure 
of the parts, we are less disposed to accept the older experi- 
ments, in which the cerebral tissue was apparently shown to 
be incapable of receiving direct artificial impressions. There 
can be scarcely any doubt with regard to the positive results 
obtained by Fritsch and Hitzig ; and it is by no means im- 
probable that further investigations may show that other 
parts of this centre are excitable. For the present, we can 
only accept the definite conclusions drawn by these physiolo- 
gists from their direct experiments, admitting that we are 
prepared to learn, from further observations, that other parts 
have analogous properties. 

Functions of the Cerebrum. 

The history of the functions of the encephalon belongs 
without question to physiology, and is one of the most exten- 

1 FRITSCH TJND HITZIG, Utber die electrische ErreglarJceit des Crrosshirns. 
Archiv fur Anatomic, Physiologic, und wissemchaftliche Mcdicin, Leipzig, 1870, 
S.' 300, el seq. 

In the London Lancet, October 21, 1871, No. xvii., p. 581, is a note stating 
tkat the experiments of Fritsch and Hitzig have been confirmed by Schiff. Schiff 
is of the opinion, however, that the movements produced by stimulation of the 
brain-substance do not depend upon direct excitability of the brain, but are re- 
flex, the result of irritation of parts concerned in tactile sensibility. As far as 
we know, the experiments of Schiff have not yet been published in full. 



FUNCTIONS OF THE CEREBRUM. 325 

sive and interesting of the subdivisions of the science ; but 
its range is so extensive, that it has long been regarded as a 
science by itself, and is only treated of exhaustively in special 
treatises on psychology. The study of psychology has been 
pursued by the method of observation much more than by 
direct experiment. It comprehends, it is true, the facts de- 
duced from experiments upon living animals, but the results 
obtained by this method are comparatively few 'and their 
scope is restricted. Nevertheless, they are sufficiently defi- 
nite ; and if these results be corrected and applied to the hu- 
man subject by a comparison with pathological facts, there 
still remains in psychology much that may be regarded as 
within the range of experimental physiology ; for pathologi- 
cal cases are very frequently available to the physiologist as 
accidental experiments indicating the functions of parts of 
the human organism. We cannot restrict ourselves, how- 
ever, to this method in the study of the intellectual phenom- 
ena ; and must draw upon facts in comparative anatomy and 
physiology, anthropology, and, finally, upon the direct obser- 
vation and classification of the intellectual processes. 

The experimental physiologist has shown that the en- 
cephalon may receive impressions and appreciate them as 
sensations ; that impressions maybe here connected and give 
rise to various of the phenomena of animal and intellectual 
existence ; that impressions are recorded by the memory ; 
and, finally, that certain parts are endowed with special func- 
tions. But beyond this, psychology is a science mainly of in- 
trospective observation ; the facts contributed by the experi- 
mentalist being few and barren. The observer of intellectual 
phenomena studies the process of development of the mind. 
He soon separates the instinctive phenomena, observed 
in the lower animals, and in the human being without expe- 
rience, from the acts which follow experience, observation, 
the recording of impressions by memory, and the generation 
of ideas. He brings his perfected intelligence to bear upon 
the process of development of the same kind of intelligence 



326 NERVOUS SYSTEM. 

in the human being progressing from infancy to adult life ; 
and finally, the psychological philosopher attempts, by intro- 
spective observation, to study the workings of the perfect 
intellect, his only means of investigation being the very in- 
telligence he is endeavoring to comprehend. 

If it were possible to bring to bear upon speculative phi- 
losophy the same positive methods employed with success in 
most of the natural sciences, the results of the study of the 
mind would be much more definite ; for we would then be 
able to eliminate much that is purely hypothetical, resting 
on no established basis in fact. As we are studying the 
mind itself with the mind, and as many psychologists en- 
deavor to submit their ideas to the test of personal expe- 
rience, it is necessary that the investigator should be entirely 
free from the disturbing elements of intellectual inaccuracy 
or unjustifiable prejudice ; but, unfortunately, the effects of 
early impressions made by faulty education are not often en- 
tirely removable ; and notions that apparently can never be 
supported by facts are apt to take the place of sound philo- 
sophic reasoning. Ideas of this kind might, perhaps, be ra- 
tionally entertained and discussed at a period when our posi- 
tive physiological knowledge amounted to almost nothing, 
as before the discovery of the circulation, when our literature 
was filled with disquisitions upon the generation of the "spi- 
ritus" the location of the passions, etc. ; but as knowledge 
has advanced and as established facts are more and more nu- 
merous and available in the study of mental phenomena, the 
range of pure speculation should become more and more re- 
stricted. 1 

At the present day, we are in possession of a sufficient num- 
ber of positive facts to render it certain that there is and can 

1 A striking example of rapid advance from the most vague and absurd 
mysticism toward positive physiological knowledge is afforded by a comparison 
of the "(Eeonomia Regni Animalis" written by Swedenborg, one of the most 
learned men of his day, in the middle of the eighteenth century, with the great 
work by Haller (Elemenla Physiologice), published only a few years later. 



FUNCTIONS OF THE CEREBRUM. 327 

be no intelligence without brain-substance ; that when brain- 
substance exists in a normal condition, intellectual phenom- 
ena are manifested, with a vigor proportionate to the amount 
of matter existing ; that destruction of brain-substance pro- 
duces loss of intellectual power ; and finally, that exercise of 
the intellectual faculties involves a physiological destruction 
of nervous substance, necessitating regeneration by nutrition, 
here, as in other tissues in the living organism. The brain 
is not, strictly speaking, the organ of the mind, for this state- 
ment would imply that the mind exists as a force, indepen- 
dently of the brain ; but the mind is produced by the brain- 
substance ; and intellectual force, if we may term the intellect 
a force, can be produced only by the transmutation of a cer- 
tain amount of matter. 

In view of these facts, which have long been more or less 
fully recognized, though not, perhaps, very accurately defined 
in words until within a few years, it is not surprising that at- 
tempts have been made to locate the different mental attri- 
butes in particular portions of the brain. 1 The old pseudo- 
science of phrenology is the most marked example of such 
an attempt ; but this has so slight a basis in fact, that it does 
not, at the present day, merit serious scientific discussion. 

In treating of the functions of the cerebrum, we shall 
not discuss psychology, except in so far as physiologists have 
been able to connect the mind, taken as a whole, with a dis- 
tinct division of the nervous system. In this we will draw 
upon experiments on living animals, facts in comparative 

1 Gall, whose labors have hardly received proper consideration at the hands 
of many physiological writers, from the fact that he is regarded as the founder 
of the untenable system of phrenology, is entitled to the credit of having im 
mensely advanced our knowledge of the anatomy of the brain ; but unfortunately, 
his visionary and unsupported theories overshadowed his merits as an exact 
anatomical investigator. As we do not enter into the early history of anatom- 
ical researches, we have not referred before to his great work in six volumes, 
which contains a large number of important facts, novel and interesting at the 
time of its publication. (GALL, Sur les fonctiom du cerveau et sur celles de cha- 
cane de ses parties, Paris, 1822-'25.) 



328 NERVOUS SYSTEM. 

physiology, in pathology, and, to a certain extent, the rela- 
tions clearly shown to exist between the development of in- 
telligence and certain of the nerve-centres, in different races 
of men and different individuals. With regard to the location 
of particular functions in distinct portions of the cerebrum, 
we have but little definite knowledge, beyond the experi- 
ments already cited in treating of the irritability of the cere- 
bral substance, and the probable location of the faculty of 
speech. The latter point will be fully discussed in its appro- 
priate place. 

Extirpation of the Cerebrum in Animals. It is, perhaps, 
sufficiently evident, from anthropological and pathological 
observations, as well as the study of comparative physiology, 
that the intellectual faculties reside in the encephalon ; but 
these methods of investigation do not clearly indicate the 
special functions of different parts of the cranial contents. 
We have seen, in our general sketch of the anatomy of the 
brain, that this is by no means a simple organ, and that cer- 
tain parts, though they are bound together by commissural 
fibres, have sufficient anatomical distinctness to lead the 
physiologist to suppose that they have separate and peculiar 
properties and functions. One of the most valuable methods 
of investigation of the functions of these separate ganglia is 
that of extirpation of one or more, leaving the others, as far 
as possible, intact. This method was first employed with 
marked success by Flourens, and has since been adopted by 
numerous experimenters. It must be remembered, however, 
that there is no subject of physiological inquiry in which it 
is so difficult to apply experiments on the inferior animals to 
the human subject, and none in which the results of experi- 
ments should be received with greater caution. The reason 
for this is apparent enough. The brain and the intellectual 
power of man are so far superior to the development of this 
organ . and its properties in the lower animals, that some 
philosophers have regarded the human intelligence as distinct 



EXTIRPATION OF THE CEREBRUM. 329 

in nature as well as in amount. Although we are by no 
means prepared to accept this proposition, regarding, as we 
must, the intelligence of man as simply superior in develop- 
ment to that of the lower animals, it is evident that this 
difference in the degree of development is so enormous as to 
render the human mind hardly comparable with the intellect- 
ual attributes of animals low in the scale. But when the 
human brain is slightly developed, as in idiots, or when 
the intellectual faculties are simply diminished in activity, 
as in certain cases of disease, the being is reduced to a condi- 
tion very like that of some of the lower animals. 

Experiments upon different classes of animals show clear- 
ly that the brain is less important, as regards the ordinary 
manifestations of animal life, in proportion as its relative de- 
velopment is smaller. For example : if we remove the cere- 
bral hemispheres in fishes or reptiles, the movements which 
we call voluntary may be but little affected ; while, if the 
same mutilation be performed in birds or some of the mam- 
malia, the diminished power of voluntary motion is much 
more marked. It would be plainly unphilosophic to assume, 
because a fish or a frog will swim in water and execute 
movements after removal of the hemispheres, very like 
those of the uninjured animal, that the feeble intelligence 
possessed by these animals is not destroyed by the opera- 
tion. It is not only possible, but probable, that in the very 
lowest of the vertebrates, the functions of the nervous cen- 
tres are not the same as in higher animals. There is, for 
example, a fish (the lancet-fish, Amphioxm lanceolatus\ that 
has no brain, all of the functions of animal life being regu- 
lated by the gray substance of the spinal cord. 1 It is essen- 
tial, in endeavoring to apply the results of experiments upon 
the brain in the lower animals to human physiology, to iso- 
late, as far as possible, the distinct manifestations of intelli- 

1 MEYXERT, in STRICKER, Handbuch der Lehre von den Geweben, Leipzig, 1868, 
S. 695 ; and, VAN DEB HOEYEN, Handbook of Zoology, Cambridge, 1858, voL il, 
p. 56. 



330 NEKVOTJS SYSTEM. 

gence, from automatic movements. Bearing in mind, then, 
the difficulties of the question and the caution with which 
all observations upon the great nerve-centres of the lower 
animals must be received in their applications to pure human 
physiology, we will proceed to discuss the phenomena follow- 
ing removal or injury of the cerebrum in direct experiments. 
In 1822 and 1823, Flourens communicated to the French 
Academy of Sciences his remarkable observations upon the 
different parts composing the encephalon. His experiments 
are so familiar to physiologists, that it is only necessary here 
to give his general conclusions. As regards the cerebral 
hemispheres, he found that the complete removal of these 
parts in living animals, frogs, pigeons, fowls, mice, moles, 
cats, and dogs, was invariably followed by stupor, apparent 
loss of intelligence, and absence even of the ordinary instinc- 
tive acts. Animals thus mutilated retained general sensibil- 
ity and the power of voluntary movements, but were thought 
to be deprived of the special senses of sight, hearing, smell, 
and taste. As regards general sensibility and voluntary 
movements, Flourens was of the opinion that animals de- 
prived of their cerebral lobes possessed sensation, but had 
lost the power of perception, and that they could execute 
voluntary movements when an irritation was applied to any 
part, but had lost the power of making such movements in 
obedience to a spontaneous effort of the will. One of the 
most remarkable phenomena observed was entire loss of 
memory and the power of connecting ideas. The voluntary 
muscular system was enfeebled, but not paralyzed. Eemoval 
of one hemisphere produced, in the higher classes of animals 
experimented upon, enfeeblenient of the muscles upon the 
opposite side, but the intellectual faculties were in part or 
entirely retained. Eemoval of even a considerable portion 
of both hemispheres was followed by no very marked effect 
as regards the intelligence. 1 

1 FLOURENS, Recherches experimenlales sur Us proprietes et les fonctions da 
systenie nerveux, Paris, 1842, pp. .18, 31, 98, etc. 



EXTIRPATION OF THE CEREBRUM. 331 

The observations of Flourens have been repeated by nu- 
merous experimentalists, and were, in the main, confirmed, 
except as regards the special senses. Bouillaud, in 1826, 
made a large number of observations on pigeons, fowls, rab- 
bits, etc., in which, after removal of the hemispheres, he 
noted the persistence of the senses of sight and hearing. 1 
Longet finally demonstrated the fact that both sight and 
hearing are retained after extirpation of the hemispheres, 
even more clearly than Bouillaud, by the following experi- 
ments: He removed the hemispheres from a pigeon, the 
animal surviving the operation eighteen days. When this 
animal was placed in a dark room and a light was suddenly 
brought near the eyes, the iris contracted and the animal 
winked ; " but it was remarkable, that when a lighted candle 
was moved in a circle, and at a sufficient distance, so that 
there should be no sensation of heat, the pigeon executed an 
analogous movement with the head." An examination after 
death showed that the removal of the cerebrum had been 
complete. An animal deprived of the hemispheres also 
opened the eyes at the report of a pistol, and gave other 
evidence that the sense of hearing was retained. 2 

AVith regard to the senses of smell and taste, it is more 
difficult to determine their presence than to ascertain that 
the senses of sight and hearing are retained. It is probable, 
however, that the sense of smell is not abolished, if the hemi- 
spheres be carefully removed, leaving the olfactory ganglia 
intact ; and there is no direct evidence that extirpation of 
the cerebrum affects the sense of taste ; indeed, in young 
cats and dogs, Longet has noted evidences of a disagreeable 
impression following the introduction of a concentrated solu- 
tion of colocynth into the mouth, as distinctly as in- the same 
animals in a normal condition. 3 

1 BOUILLAUD, Recherches experimentales sur lesfonction* ducerveau. Journal 
de physiologic, Paris, 1830, tome x., p. 36, et seq. 

2 LOSGET, Traite de physiologic, Paris, 1869, tome iii., pp. 328, 329. 
8 Op. efc, p. 430. 



332 NERVOUS SYSTEM. 

We will now proceed to describe, as accurately as possi- 
ble, the condition of an animal after complete extirpation of 
the cerebrum, as observed in numerous experiments that we 
have ourselves made on this subject, premising the statement 
that these are merely repetitions of observations made by 
other physiologists. 

A pigeon, in a perfectly normal condition, is deprived 
of the hemispheres, by removing the calvarium and carefully 
scooping out the parts with the handle of a scalpel. This 
operation is usually not difficult, and the haemorrhage is soon 
arrested spontaneously. The slit in the scalp is closed with 
sutures, and the animal is set at liberty. 

The appearance of the animal after this mutilation is 
peculiar and characteristic. There immediately supervenes 
a condition of stupor. There is usually no attempt at move- 
ment, and, though the pigeon stands upon its feet, the head 
is almost buried in the feathers of the neck, the eyes are 
closed, and the attitude is one of absolute indifference to 
surrounding conditions. The muscles seem to act with just 
sufficient vigor to maintain the standing position. If we 
pinch one of the toes, or grasp the beak, there is evident 
sensation, and a persistent and more or less vigorous effort 
is made to release the part. It is sufficiently evident, from 
these and other tests, that sensation and the power of volun- 
tary motion are retained ; but as soon as the animal is left 
quiet, it relapses into its stupid condition, makes no effort 
to escape, and apparently loses immediately all recollection 
of having been disturbed. The irritation has evidently pro- 
duced a sensation of discomfort, and has given rise to a 
voluntary muscular effort ; but there has been no idea of 
danger, nor an intelligent effort to avoid a repetition of the 
disagreeable or painful impression. 

It is easy to demonstrate, by experiments such as we 
have just alluded to, that the animal sees and hears, and 
retains the sense of taste ; but it connects no idea with any 
thing seen, and the report of a pistol, which, under natural 



EXTIRPATION OF THE CEEEBBUM. 333 

conditions, would excite terror and an idea of danger, simply 
causes the pigeon to give evidence that the sound has been 
heard. As we have already stated, it is probable that the 
animal has the sense of smell, but it is difficult, if not im- 
possible, to establish this point experimentally. The same 
remark applies to the sensations of hunger and thirst. The 
animal may feel the want of water and food, but, it has no 
idea of relieving these sensations by drinking and eating, 
and, if left to itself, will die of inanition. 

There has been a great deal of discussion among experi- 
mentalists with regard to spontaneous voluntary movements 
in animals deprived of the cerebral hemispheres. The ex- 
perimental conditions necessary for determining this point 
are the following : The observer must be certain that the 
removal of the hemispheres has been complete ; for it has 
been clearly shown that even when a small amount of cere- 
bral substance has escaped, the functions of these lobes are 
not entirely abolished. Again, we must be equally certain 
that movements which seem to be due to a spontaneous act 
of volition take place when the animal has not been aroused 
from the condition of stupor which results from the opera- 
tion. Generally, when the animal is left to itself, the con- 
dition of stupor persists ; but when aroused by artificial 
means, it will walk a few steps, plume the feathers, shake 
its head, and make various voluntary movements without 
further irritation, soon relapsing, however, into somnolency. 
One of the most accurate and reliable of the recent observ- 
ers of these phenomena, Yulpian, asserts without reserve, 
that an animal, deprived completely of the cerebral hemi- 
spheres, is incapable of a spontaneous voluntary effort ; and 
we are inclined to an unqualified adoption of this opinion. 
"With regard to a rabbit, from which Yulpian had removed 
the cerebral hemispheres and the corpora striata, he makes 
the following statement : " I do not hesitate to say that this 
rabbit is completely deprived of spontaneous volition. All 
its movements, which are, indeed, much less varied than 



334 NERVOUS SYSTEM. 

those of a bird operated on in the same manner, are ex- 
clusively and directly due to a stimulation produced by 
exterior excitations, or by interior inclinations, such as fa- 
tigue, etc." l 

In view of the very great variety of movements that 
occur in animals after removal of the cerebrum, it is quite 
difficult to define precisely what movements are due to vol- 
untary action depending upon some external or interior im- 
pression, which are really reflex voluntary movements, and to 
distinguish them from those which arise from a spontaneous 
and, perhaps, an intelligent effort of the will. These points 
have been so admirably described in a recent article, by 
Onimus, that we quote his concluding summary : 

" As a summary, in the inferior animals, as- in the supe- 
rior animals, the removal of the cerebral hemispheres does 
not cause to disappear any of the movements that previous- 
ly existed. Only, these movements assume certain peculiar 
characters. In the first place, they are more regular, they 
have the true normal type, for no psychical influence inter- 
venes to modify them ; the locomotor apparatus is brought 
into action without interferences, and one could almost say 
that the ensemble of movements is then more normal than 
in the normal condition. 

"In the second place, the movements executed take 
place inevitably after certain excitations. It is a necessity 
that the frog placed in water should swim, and that the 
pigeon thrown into the air should fly. The physiologist 
can then, at will, in an animal without the brain, determine 
such and such an act, limit it, arrest it ; he can anticipate 
the movements and affirm in advance that they will take 
place under certain conditions, absolutely as the chemist 
knows in advance the reactions that he will obtain in mix- 
ing certain bodies. 

" Another peculiarity in the movements that take place, 
when the cerebral lobes are removed, is their continuation 

1 VULPIAN, Systems nerveux, Paris, 1866, p. 680. 



EXTIRPATION OF THE CEREBRUM. 335 

after a first impression. On the ground, a frog without the 
brain when irritated makes, in general, two or three jumps 
at the most ; it is rare that it makes but one. Placed in 
water, it continues the movement of natation until it meets 
with an obstacle ; it is the same in the carp, eel, etc. The 
pigeon continues to fly, the duck and goose continue to 
swim, etc. We should say that there is a spring which 
needs for its action a first impulsion, and which is stopped 
by the slightest resistance. But, what is striking, is pre- 
cisely that continuation of the condition once determined, 
and we cannot refrain from connecting the facts observed in 
an animal deprived of the cerebral lobes with those which 
constitute the characteristic properties of inorganic matter. 
Brought into movement, the animal without a brain retains 
the movement until there is exhaustion of the conditions of 
movement, or until it meets with resistance ; taken in re- 
pose, it remains in the state of inertia until an exterior 
cause intervenes to bring it out of this condition. It is 
living, inert matter." l 

There is now no room for discussion with regard to the 
persistence of general sensibility after removal of the hemi- 
spheres. The experiment upon a pigeon leaves no doubt 
upon this point ; but the susceptibility to pain has been 
much more strikingly illustrated in other animals. Yulpian, 
in describing the condition of animals operated upon in this 
way, illustrates the persistence of sensibility in rats and rab- 
bits, by the violent cries which follow painful impressions. 2 

In concluding our consideration of the observations upon 
inferior animals, it only remains for us to discuss briefly cer- 
tain late experiments, which have attracted a great deal of 
attention, from the fact that they seem to show that sponta- 
neous volition exists after complete extirpation of the cere- 
brum. These experiments have been most ably and satis- 

1 OXIMUS, Reclierches experimentaJ.es sur les phenomenes consecutifs d Tablation 
du cerveau. Journal de t anatomic, Paris, 1870-"7l, tome vii., p. 644. 

2 VULPIAN, Systeme nerveux, Paris, 1866, p. 667. 

122 



336 NERVOUS SYSTEM. 

factorily analyzed by Yulpian. 1 Goltz argues, from experi- 
ments on frogs and the movements executed after extirpation 
of 'the brain, that these animals make intelligent muscular 
efforts when deprived of the hemispheres ; and the phenom- 
ena observed after this mutilation are indeed very curious. 
As was shown by Yulpian, in his own experiments, frogs and 
fishes thrown into water will swim about and the frogs will 
even succeed in getting out of the water, but then they im- 
mediately relapse into a torpid condition. We do not con- 
ceive that these facts are in opposition to the statement just 
made with regard to the absence of spontaneous volition in 
birds and the mammalia, particularly in view of the slight 
importance of the functions of the cerebrum as compared with 
the spinal cord in the lower orders of vertebrate animals. 
The views lately advanced by Yoit are based upon an iso- 
lated experiment upon a pigeon that was kept alive for five 
months after the cerebral lobes had been, as stated by Yoit, 
completely removed. At first the pigeon presented the phe- 
nomena usually observed after this operation ; but it gradu- 
ally recovered, until finally it seemed entirely normal, with 
the single exception that it never would eat, all food being 
introduced forcibly. Five months after the operation, the 
pigeon was killed and the encephalic cavity was found filled 
with a white substance containing dark-bordered nerve-fibres 
and 'nerve-cells. Yoit never before observed any thing like 
regeneration of the nervous substance or so complete a res- 
toration of the cerebral functions ; and he regarded this as 
an instance of anatomical and physiological regeneration of 
the hemispheres. The objections to accepting this observa- 
tion with the physiological conclusions presented by Yoit 
are, that it is not only possible but probable, that the hemi- 
spheres were not entirely removed, and that the posterior 
portion of the encephalon had advanced to occupy in part 
the space originally filled by the extirpated mass. 2 "While 

1 Archives de physiologic, Paris, 1869, tome ii., p. 301. 

5 GOLTZ, Contributions d Petude des fonctions du cerveau de la grenouille ; 



FUNCTIONS OF THE CEREBRUM. 337 

we do not assume that anatomical and functional regenera- 
tion of the cerebrum in a pigeon is impossible, it must be 
admitted that such an extraordinary statement as that made 
by Yoit cannot be accepted without reserve, upon the basis 
of a single observation. 1 

Pathological Facts bearing upon the Functions of the 
Cerebrum. A careful study of the phenomena which attend 
certain pathological conditions of the brain in the human 
subject, such as laceration or pressure from effusion of blood, 
softening of the nervous substance, etc., taken in connection 
with the results _of experiments upon living animals, throws 
considerable light upon the functions of certain distinct por- 
tions of the encephalon. Cerebral haemorrhage very common- 
ly involves the corpus striatum, either directly or indirectly, 
and then we have paralysis of motion limited to the side of 
the body opposite to the lesion. When the optic thalamus is 
affected, there is impairment of sensibility upon the opposite 
half of the body. These facts illustrate the course of the 
motor and sensory conductors from and to the cerebrum. 
It is not very common to observe lesions confined to the 
gray or white substance of the hemispheres, but when this 
occurs, and when there is no pressure upon the corpora 
striata or optic thalami, there is no paralysis of motion or 
sensation, though there may be a certain amount of weak- 
ness of the muscles upon the side of the body opposite to 
the injury. Experiments upon the inferior animals have 

ROSEXTHAL, Sur les mouvements qui ont lieu apres Fablation des hemispheres 
cerebraux ; Sur un pigeon auquel le professeur Volt avail enleve les hemispheres 
cerebraux dans le mcis de juillet 1861 ; YOIT, Observations sur Fablation des 
hemispheres cerebraux chcz le pigeon. .Archives de physiologic, Paris, 1869, tome 
ii., p. 301. 

1 YOIT, Phenomenes qui suivent Fablafion des hemispheres du cerveau chez les 
pigeons. Revue des cours scientifiques, Paris, 1868-1869, tome vi., p. 256. 

This observation has already been detailed in full, in connection with the 
question of the possible regeneration of the nerve-centres after extirpation, 
(See page 63.) 



338 NEKVOUS SYSTEM. 

confirmed the conclusions to be drawn from these pathologi- 
cal facts. In frogs, fishes, and birds, when one hemisphere 
has been removed, the evidences of feebleness of the muscles 
of the opposite side are not very marked ; but they are quite 
distinct in the adult mammalia. Yulpian noted, in experi- 
ments upon dogs, that the destruction of a portion of one 
cerebral hemisphere produced feebleness, but a very incom- 
plete paralysis of motion upon the opposite side. 1 

It is a fact now generally admitted in pathology, that loss 
of cerebral substance from repeated haemorrhage is sooner 
or later followed by impairment of the intellectual faculties. 
This point it is frequently difficult to determine in a single 
instance, but an analysis of a sufficient number of cases 
shows impaired memory, tardy, inaccurate, and feeble con- 
nection of ideas, abnormal irritability of temper, with a child- 
ish susceptibility to petty or imaginary annoyances, easily- 
excited emotional manifestations, and a variety of phenom- 
ena denoting abnormally feeble intellectual power, following 
any considerable loss of cerebral substance. In short, patho- 
logical conditions of the brain all go to show that the intel- 
lectual faculties reside in the cerebral hemispheres. 

As a final argument drawn from pathology, in favor of 
the view just stated, we have only to allude to the size of 
the brain in certain cases of idiocy. Prof. Hammond, in his 
admirable work on " Diseases of the Nervous System," has 
cited several examinations of the brain in idiots, in which 
this organ has been found to be less than one-half of the 
ordinary weight ; as the cases reported by Tiedemann, of 
19f, 25f , and 22^- ounces, in three idiots, whose ages were, 
respectively, sixteen, forty, and fifty years. 2 A case was 
reported by Mr. Gore, of an idiotic woman, forty-two years 
of age, whose brain weighed ten ounces and five grains ; 3 

1 VULPIAN, Systcme nerveux, Paris, 1866, p. 677. 

2 HAMMOND, Diseases of the Nervous System, New York, 1871, p. 326. 

3 GORE, Notice of a case of Micro-ccphaly. Anthropological Review, London, 
1863, No. i., p. 170. 



FUNCTIONS, OF THE CEKEBEUM. 339 

and one is reported by Mr. Marshall, of an idiotic boy, twelve 
years old, whose brain weighed but 8^ ounces. 1 Mr. Brad- 
ley, in a late number of the Journal of Anatomy and Phys- 
iology^ gives an elaborate description of the brain of an 
idiot, thirty-five years of age, extremely emaciated at the 
time of his death, when he weighed but sixty pounds. The 
encephalon, including the cerebrum, cerebellum, and pons, 
weighed twenty-eight ounces, and the proportion of the 
cerebellum to the cerebrum was as 1 to 5 '5. In the healthy 
adult male, of ordinary weight, the encephalon weighs fifty 
ounces, and the proportion of the cerebellum to the cerebrum 
is as 1 to 8f. Mr. Bradley calls attention to the proportion 
of the cerebellum to the cerebrum in this case, stating that 
this is common in the encephalon of idiots. 2 In idiots, the 
weight of the body is generally much below the normal stand- 
ard ; and in the case reported by Bradley, the proportionate 
weight of the encephalon to that of the entire body is even 
greater than in the healthy adult. If, for example, we double 
the weight of the body and the brain, we would have, for 
one hundred and twenty pounds of weight, an encephalon 
of fifty-six ounces. This. point, however, cannot be admitted 
as an argument against the fact that congenital idiocy is 
usually attended with an abnormally small development of 
the hemispheres. Most idiots take little or no exercise ; they 
are under-sized, and have but little muscular vigor ; and it is 
probable that the general development of the body is more 
or less a consequence of the abnormal cerebral condition. 

1 MARSHALL, Brain and Calvarium of a Microcephale. Anthropological He- 
view, London, 1863, No. ii., Appendix, containing the Transactions of the An- 
thropological Society of London, p. ix. 

2 BRADLEY, Description of the Brain of an Idiot. Journal of Anatomy and 
Physiology, Cambridge and London, 1871, vol. vi., p. 67. 

Gratiolet, in an article on microcephaly, states that the development of the 
cerebellum, in proportion to the size of the cerebrum, is enormous, and that 
the reduction in the size of the encephalon is almost exclusively in the cerebral 
hemispheres. (Memoire sur la microcephalie. Journal de la physiologic, Paris, 
1860, tome iii., p. 115.) 



34:0 NEKVOUS SYSTEM. 

We might compare the weight of the body in Mr. Bradley 's 
case with that of a child from seven to fourteen years of age ; 
and at this period of life, according to the tables compiled 
by Quain, the average weight of the encephalon is 45-96 
ounces, for the male, and 40*78 ounces, for the female. 1 

The statements just made with regard to the brains of 
idiots refer to cases characterized by complete absence of in- 
telligence, and furthermore, probably, by very small develop- 
ment of the body. On the other hand, there are instances 
of idiocy, the body being of ordinary size, in which the weight 
of the encephalon is little if any below, the average. Lehit 
reports several cases of this kind. In one of these, a deaf- 
mute idiot, forty-three years of age, a little above the ordinary 
stature, presenting " idiocy of the lowest degree ; no speech ; 
almost no sign of intelligence ; no care for cleanliness," the 
encephalon weighed 48'32 oz. Other cases of idiots of 
medium stature are given, in which the brain weighed but 
little less than the normal average. a These facts illustrate 
the difficulty of subordinating individual observations to any' 
general rule, and this is particularly marked with regard to 
the brain, the structure of which is so complex and difficult 
of investigation. 

Comparative Development of the Cerebrum in the Lower 
Animals. It is only necessary to refer very briefly to the de- 
velopment of the cerebrum in the lower animals as compared 
with the human subject, to show the connection of the hemi- 
spheres with intelligence. In man, the cerebrum presents an 
immense preponderance in weight over other portions of the 
encephalon ; and in some of the lower animals, the cerebrum 
is even less in weight than the cerebellum. In man, also, not 
only the relative but the absolute weight of the brain is greater 
than in lower animals, with but two exceptions. Todd cites 

1 QUAIN, Elements of Anatomy, London, 1867, vol. ii., p. 569. 

2 LELUT, Du poids du ccrveau considere dans ses rapports avec le developpement 
de T intelligence. Physiologic de lapensee, Paris, 1862, tome ii., p. 308. 



THE CEREBRUM IX DIFFERENT RACES, ETC. 341 

a number of observations made upon the brains of elephants, 
in which the weights ranged from nine to ten pounds. 1 
Rudolphi gives the weight of the encephalon of a whale, 
seventy-five feet long, as considerably over five pounds. 2 
With the exception of these animals, man possesses the 
largest brain in the zoological scale. 

Another interesting point in this connection is the de- 
velopment of cerebral convolutions in certain animals, by 
which the relative amount of gray matter is increased. In 
fishes, reptiles, and birds, the surface of the hemispheres is 
smooth ; but in many mammalia, especially in those remark- 
able for intelligence, the cerebrum presents a greater or less 
number of convolutions, as it does in the human subject. 3 

Comparing the relative size of the brain, its complexity 
of organization, and the increase of its gray substance by 
convolutions, with the development of intelligence in the 
animal scale, it is so evident that the cerebrum is the seat of 
the intellectual faculties, that this point in our argument 
seems to need no farther discussion. 



Development of the Cerebrum in Different Races of 
and in Different Individuals. It may be stated as a general 
proposition, that in the different races of men, the cerebrum 
is developed in proportion to their intellectual power ; and 
in different individuals of the same race, the same general 
rule obtains. Still, this law presents marked exceptions. 
Certain brains in an inferior race may be larger than the 
average in the superior race ; and it is frequently observed 
that unusual intellectual vigor is coexistent with a small 
brain, and the reverse. These exceptions, however, do not 
take away from the force of the original proposition. As 

1 TODD, Cydopcedia of Anatomy and Physiology, London, 1839-'47, vol. iii., 
p. 664, Article, Nervous Centres. 

8 RUDOLPHI, Grundlss der Physiologic, Berlin, 1823, Bd. ii., Erste Abthei- 
lung, S. 12. 

3 VAX DER HOEVEN, Handbook of Zoology, Cambridge, 1858, vol. ii., pp. 42, 
227, 358, 596. 



342 NEKVOUS SYSTEM. 

regards races, the rule is found invariable, when a sufficient 
number of observations are analyzed, and the same holds 
true in comparing a large number of individuals of the same 
race. Average men have an advantage over average women 
of about six ounces of cerebral substance ; and, while many 
women are far superior in intellect to many men, such in 
stances are not sufficiently numerous to invalidate the general 
law, that the greatest amount of intellectual capacity and 
mental vigor goes with the greatest quantity of cerebral sub- 
stance. If we accept the view, which is in every way rea- 
sonable, that the gray substance of the cerebral hemispheres 
is the generator of the mind, it would be necessary, in com- 
paring different individuals with the view of establishing a 
definite relation between brain-substance and intelligence, 
to estimate the amount of gray matter ; but it is not easy 
to see how this can be done with any degree of accuracy. 

It is undoubtedly true that proper training and exercise 
develop and increase tho vigor of the intellectual faculties ; 
and that thereby the brain is increased in power, as are the 
muscles, under analogous conditions. This will perhaps ex- 
plain some of the exceptions above indicated ; but an addi- 
tional explanation may be found in differences in the quality 
of brain-substance in different individuals, independently of 
the size of the cerebral hemispheres. One evidence that 
these differences in the quality of intellectual working matter 
exist is, that some small brains actually accomplish more 
and better work than some large brains. This fact mny be 
due to differences in training, to the extraordinary develop- 
ment in some individuals of certain qualities, to intensity 
and pertinacity of purpose, capacity for persistent labor in 
certain directions, a fortunate direction of the mental efforts, 
opportunity and circumstances, etc. But, aside from these 
considerations, there are analogies in the muscular system, 
which render it exceedingly probable that there are impor- 
tant individual differences in the quality of generating ner- 
vous matter. 



THE CEREBRUM IX DIFFERENT RACES, ETC. 34:3 

TTe have in our mind at this moment two persons, in a 
condition of perfect health and muscular development, who 
have devoted about fifteen years to the same kind of athletic 
exercise, but who present the most marked differences in 
muscular power. One of these has an enormously-developed 
muscular system, the muscles being large and as hard as is 
ever seen. In this individual, the arm over the biceps meas- 
ures seventeen inches in circumference. He can raise from 
the shoulder with the right hand and stand erect with the 
arm straight under a weight of a little less than one hundred 
pounds. The other individual has muscles of about the same 
hardness, but very much smaller. His arm measures over 
the biceps a little more than fourteen inches ; but he can 
raise from the shoulder a weight of one hundred and thirty- 
eight pounds. A third individual can " put up " from the 
shoulder, a dumb-bell of the enormous weight of one hundred 
and eighty-one pounds. This feat we have seen executed, 
and have accurately verified the weight. The gentleman 
referred to, Mr. Richard A. Pennell, of Xew York, is not a 
professional gymnast, but is one of the strongest men, in this 
particular exercise, on record, certainly in this country. His 
height is five feet ten inches ; weight, one hundred and 
ninety-five pounds, without clothing ; his muscles are large, 
but rather soft. As this exhibition of muscular power is, 
we believe, almost unparalleled, we may state that the weight 
is pushed slowly and gradually from the shoulder, the arm is 
straightened, and the body is brought to an erect position 
under the weight, which is held perfectly balanced in the 
right hand for several seconds. Less striking examples of 
such differences in muscular quality are innumerable, and 
must have been observed by those interested in athletic exer- 
cise ; and in view of this, it seems not only possible but prob- 
able, that the generating portion of the nervous system pos- 
sesses analogous differences in quality in different persons. 

In concluding this portion of our argument, we present 
a table of an exceedingly interesting series of observations 



344 JS'ERVOUS SYSTEM. 

of the comparative weights of the encephalon in the Cauca- 
sian, tue negro, and the intermediate grades produced by the 
union of the two races. The observations in this table are 
hardly sufficient in number to establish the exact relations 
between the brains in the different grades of color, but they 
illustrate points of peculiar interest in this country, where 
the blacks are so numerous, a- 1 1 where the union of the two 
races, white and black, is so common. As far as the re- 
sults go. they are in decided opposition to those given by 
Tiedemann, in his remarkable memoir on the brain of the 
negro. 1 

We also give a list of some of the well-authenticated 
weights of the encephalon in men whose intellectual faculties 
had been observed during life. 2 This latter list we have pre- 
pared with great care, and have introduced some observa- 
tions not found in the works on physiology. In estimating 
the intellectual power of individuals, it is difficult to arrive 
at exact conclusions, except with regard to men of acknowl- 
edged eminence. Still, the statements are as accurate as 
possible, and must be taken for what they are worth. Sev- 
eral of the examples given in this list are marked exceptions 
to the general rule, that the mental vigor is in proportion to 
the development of brain-substance. 9 

1 TIEDEMANN, Das Him des Negers, Heidelberg, 1837. 

2 We have not considered it necessary to enter into a discussion of the rela- 
tions of the facial angle to intelligence, in the lower animals and in different 
races of men. It was proposed by Camper to take the angle made at the junc- 
tion of two lines, one drawn from the most projecting part of the forehead to 
the alveolae of the teeth of the upper jaw, and another passing horizontally back- 
ward from the lower extremity of the first line, as the facial angle. This angle 
is, to a certain extent, a measure of the projection of the anterior lobes of the 
brain. Numerous observations upon the facial angle in different races were 
made by Camper and other physiologists and ethnologists. They show, in gen- 
eral terms, that the angle is larger in man than in any of the inferior animals, and 
is largest in those races that possess the greatest development of intellectual 
power. (CAMPER, Dissertation physique sur les differences reelles que presentent 
les traits du visage, etc., Autrecht, 1791. BROCA, Sur tangle facial ft le triangle 
facial. Mhnoires d'anthropologie, Paris, 1871, tome i., p. 110.) 



THE CEREBRUM IN DIFFERENT RACES, ETC. 



345 



Ethnological Table, derived from 405 Autopsies of White and .Negro 
Brains. Made under the direction of Surgeon Ira Russell, llth 
Massachusetts Volunteers. 1 





* 




4. 


Tn 


2 


| 





q 


9 


i 




f) 




of Antopsi 


1 


\t 


o 

= 

6 


| 


& 

s 


iis, :>:. JUKI 

dcr (ill ox,. 


ns, 50 and 
dcr 55 oz. 


1 


ns, 40 and 

dcr If) o-/.. 


ns, 85 and 

dcr -10 (>/. 


! 




1 


O 


< 




a 

i 


| 


1 


1 


1 ' 


2 

- 


- 


1 




24 


White 


52-06 


64 


-44| 


1 


4 


11 


7 


1 


. 


. 




25 


1 ' 


49-05 


51 


40 


1 


_ 


10 


12 


2 




. 




47 


' 


47-07 


57 


37 s - 




2 


13 


19 


12 


1 






51 


i < 


46-54 


59 


38 


. 


2 


10 


22 


11 


6 


. 




95 




46-16 


57 


34^ 




1 


15 


50 


21 


7 


1 




22 


i^ i 


45-18 


60* 


40 


. 


. 


3 


10 


9 


. 


. 




141 


Black 


46-96 


56 


35 1 





5 


42 


51 


38 


3 







405 










2 


14 


104 


171 


94 


17 


1 


Autopsies of 




Whites, 






















Clendinning, 




collated 






















Sims, Reid, 




from 






















and 




various 






















Tiedemann 


278 


sources 


49^ 


65 


34 


7 


28 


99 


97 


39 


7 


1 



Ta&Ze o/ Weights of the EncepJialon, in ounces, av., in Individuals, in 
some of whom the Degree of Intelligence is more or less accurately 
known, 

1. Cromwell, 2 aged 59 (not accepted by physiologists) 

2. Byron, 3 aged 36 (not accepted by physiologists) 

3. Cuvier, aged 63 

4. Abercrombie, aged 63 



82-29 oz. 
79-00 " 
64-33 " 
63-00 " 



1 SAXFORD B. HUNT, The Negro as a Soldier. Quarterly Journal of Psycho- 
logical Medicine, Xew York, 1867, vol. i., p. 182. 

2 Weight taken from WAGNER, Fonctions du cerveau. Journal de la phy- 
sioloyie, Paris, 1861, tome iv., p. 556. Soemmerring (De Corporis Humani 
Fali'ica, Trajecti ad Moenum, 1798, tomus iv., p. -38) states that he examined 
the skull of Cromwell, and thinks, from the size of the cranial cavity, that the 
weight of the brain ordinarily given must be inaccurate. 

3 Dissection of Lord Byron. Medico- Chirurgical Review, London, 1825, vol. 
.i. (American Reprint), p. 164. The statement is quoted from the Gazette de 
sante, 25 August, 1824, that " tiie cerebmm and cerebellum weighed six medi- 
cinal pounds" This equals 79 oz. av., less 25 grains. This statement is made 
on the authority of Dr. Bruno, and is certainly inaccurate, especially as many 
biographers of Byron state that his head was unusually small. 



346 NERVOUS SYSTEM. 

6. Ruloff, aged 53; above medium stature; executed for murder, in 
1871 ; well versed in languages, imagining that he had dis- 
covered new and important principles in philology . . . 5 9 '00 oz 

6. James Fisk, Jr., 1 aged 37 ; killed in New York, in 1872 ; illiterate, 

but said to possess great executive ability ; notorious for co- 
lossal and unscrupulous financial speculations . . . 58*00 " 

7. Spurzheim 55*06 " 

8. Adult man; 2 an idiot since two years of age .... 64*95 " 

9. Laborer, 2 aged 22 ; died of fracture of the pelvis . . . 53*79 " 

10. Daniel Webster, aged 70 63-50 " 

11. Celebrated mathematician, 2 aged 54; above the ordinary stature 53*41 " 

12. Executed criminal, 3 aged 45 ; medium stature; of less than ordi- 

nary intelligence, and uncultivated 53*12 " 

13. Celebrated clinical professor, 2 aged 62 ; medium stature . . 52*88 " 

14. Mathematician of the first rank, 2 aged 78 ; medium stature . 52*62 " 

15. Executed criminal, 3 aged 34 ; rather large in stature ; ordinary in- 

telligence, but singular, and somewhat cultivated . . . 50*09 " 

16. Dupuytren, aged 58 49*68 " 

17. Day-laborer, 2 aged 49 48*85 " 

18. Executed criminal, 3 aged 29 ; medium stature ; of scarcely ordi- 

nary intelligence, and uncultivated 48*81 " 

19. Executed criminal, 4 aged 42 ; a little above medium stature ; in- 

telligence fine, developed, and slightly cultivated . . . 48*81 " 

20. Idiot, of a very low degree of intelligence ; 4 aged 37 ; a little above 

medium stature ; movements very active .... 48*67 " 

21. Deaf-mute, 4 aged 43 ; a little above medium stature ; an idiot, of 

the lowest degree of intelligence 48*32 " 

22. Executed criminal, 4 aged 46 ; medium stature ; of ordinary intelli- 

gence, uncultivated, but proud and vivacious . . . 48*14 " 

23. Man, slightly imbecile, 4 aged 67 ; medium stature . . . 48*14 " 

24. Man about 60 years of age 5 48*14 " 

25. Celebrated philologist, 5 aged 54 ; 5 feet 7 inches tall . . 47*90 " 

26. Executed criminal, 4 aged 34 ; small stature ; intelligence developed 

and cultivated 47 '79 " 

27. Man, about 24 years of age ; 5 died of aortic insufficiency . . 47*69 ' 

28. Day-laborer, 5 aged 51 . 47*44 " 

29. Man 34 years of age; 5 died of pneumonia 47*26 " 



1 This is taken from the official report of the autopsy of James Fisk, Jr., by 
Dr. E. T. T. Marsh, deputy coroner, on file in the office of the district attorney, 
in the city of New York. The cerebrum weighed 51 ounces; the cerebellum, 
6 oz., and the pons, 1 oz. 

2 WAGNER, Journal de la physiologic, Paris, 1861, tome iv., p. 558. 

8 LELUT, Physiologic de la pensec, Paris, 1862, tome ii., pp. 304-310. 
4 LELUT, loc. cit. 6 WAGNER, loc. cit. 



THE CEREBRUM IX DIFFERENT RACES, ETC. 347 

30. Brigand and assassin, 1 aged 32 ; beheaded 46*91 oz. 

31. Idiot of the lowest degree of intelligence, 2 aged 24 ; medium stature 46*56 " 

32. Executed criminal, 8 aged 27 ; medium stature ; of ordinary and 

uncultivated intelligence 46*21 " 

33. Executed criminal, 2 aged 40 ; at least of medium stature ; intelli- 

gence developed and cultivated 46*21 " 

34. Railroad laborer, 1 aged 23 46*21 " 

35. Executed criminal, 2 aged 29; intelligence hardly ordinary, and 

uncultivated 45-50 " 

36. Wood-cutter, 1 aged 57 ; died of vertebral caries . . . 44*90 " 

37. Idiot, below the condition of a brute ; 2 aged 39 ... 44'30 u 

38. Imbecile, with difficulty in movements ; 2 aged 57 ; intelligence 

correct, notwithstanding its slight development . . . 43*56 " 

39. Man, 34 years of age ; 1 died of phthisis 43*38 " 

40. Celebrated mineralogist, 1 aged 77 ; above medium stature . . 43*24 " 

41. Executed criminal, 2 aged 31; small stature; intelligence mobile 

and exaggerated 42*04 " 

42. Upholsterer, 1 aged 60 ; died of phthisis 40*91 " 

43. Imbecile, 5 aged 23 ; large stature 38*97 " 

44. Idiot, of the lowest degree of intelligence ; 2 aged 46 ; medium 

stature 36*86 " 

45. Man, 46. years of age ; 2 idiocy very profound ; very large stature 36*15 " 

46. Man, 44 years of age ; 2 idiocy very profound ; a little below me- 

dium stature .... 34*39 " 

In compiling the foregoing table, we have in every in- 
stance consulted the authentic reports of the weights of the 
brain, and have reduced them all to ounces av. with the 
greatest care. This was found necessary, on account of the 
important variations in the reports quoted by different phys- 
iological authors, especially as regards the brains of Cuvier, 
Webster, and Dupuytren. "We believe that our figures are 
absolutely correct. The weights of the brains of Cromwell 
and Byron are given, but there can be hardly any question 
that they are grossly exaggerated. 

In the report of the autopsy of Cuvier, the weight of the 
brain is given as "trois livres onze onces quatres gi*os et 
demi" : Cuvier died in 1832, and the weight is in the old 

1 WAGXER, loc. cit. 2 LELUT, loc. fit. 

3 Note sur la maladie et la mort de G. Cuvier. Archives generates de mede- 
line, Paris, 1832, tome xxix., p. 144. 



348 NERVOUS SYSTEM. 

poids de marc" l the livre = 7,561 troy grains. The weight 
above given, reduced to ounces av., = 64-33. 

The weight of the brain of Abercrombie is taken from 
the original report furnished by Dr. Adam Hunter. 2 The 
weight of the brain of Kuloff is taken from a full report of 
the autopsy in the Psychological Journal. 3 The weight of 
the brain of James Fisk, Jr., was furnished by Dr. Edward 
T. T. Marsh, Deputy Coroner of New York, who conducted 
the autopsy. 4 The weight of Spurzheim's brain was taken 
from the Medico- Qhirurgical Review? 

The report of Daniel "Webster's brain is certainly a curi- 
osity in scientific literature. In the account .of the autopsy, 
by Dr. Jeffries, of Boston, the actual weight of the enceph- 
alon, taken by that most accurate and reliable observer, Dr. 
Jeffries "Wyman, was 5 3 '5 oz. av. It is stated, however, by 
Dr. Jeffries, that " the weight of the brain deviated much 
less from the average than the measurements ; it was en- 
tirely out of proportion to the unusual dimensions of the 
cranial cavity. . . . Both serum and lymph, there can be no 
doubt, encroached upon and occupied the space once filled 
with cerebral substance. The weight given above, there- 
fore, cannot be regarded as being equal to the weight of , the. 
brain in a state of health." To supply this hypothetical de- 
ficiency in cerebral substance in this remarkable man, Dr. 
Jeffries, aided by Prof. Treadwell, of Cambridge, makes an 

1 In 1812, by a ministerial decree, the livre was fixed at 500 grammes, in- 
stead of 489'5 grammes, the equivalent of the livre poids de marc ; but the old 
weight was generally in use in 1832, and all of the calculations, both for Cuvier 
and Dupuytren, are from the poids de marc. As far as we can ascertain, the 
livre of 500 grammes was little used, and should not be taken, unless expressly 
stated. 

2 Account of the late Dr. Abercrombie. Edinburgh Medical and Surgical 
Journal, Edinburgh, 1845, vol Ixiii., p. 448. 

3 BURR, Medico-legal Notes on the Case of Edward H. Rulo/. Journal of Psy- 
chological Medicine, New York, 1871, vol. v., p. 738. 

4 Written communication from Dr. Marsh. 

5 The STcull of Spurzheim. Medico- Chirurgical Review, London, 1836, New 
Series, vol. xxv. (American Reprint), p. 448. 



THE CEREBROI IX DIFFEKEXT KACES, ETC. 349 

approximative calculation, based upon the cranial capacity, 
the specific gravity of the brain (according to Cruveilhier, 
and not the actual specific gravity of the brain examined), 
and arrives at the conclusion that " Mr. Webster's brain will 
be found to rank among those whose brains are generally 
cited as instances of remarkable size." The brain of Cuvicr 
is then given as weighing 64J oz. ; Webster, 63f pz. ; and 
Abercrombie, 63 oz. It is impossible to avoid the suspicion, 
in reading this report, that an attempt is made to make the 
weight of the brain accord with the acknowledged remark- 
able intellectual power of Mr. Webster, as well as the un- 
usual cranial capacity. 1 

The account of Dupuytren's brain, the weight of which 
is often misquoted by authors, is taken from the official re- 
port of the autopsy, published in the Revue medicate. The 
encephalon weighed 2 livres, 14 onces. Taking this z&poids 
de marc, the weight is 49'68 oz. av. 3 

The other weights given in the table are taken from 
Lelut 3 and Wagner. 4 

A careful study of the weights given in the preceding 
table shows the impossibility of applying to individuals an 
absolute rule that the greatest brain-power is connected with 
the greatest amount of brain-substance. The men of acknowl- 
edged intellectual ability in the table are, Cuvier, Abercrom- 
bie, Spurzheim, Webster, Dupuytren, and those cited by 
Wagner as celebrated mathematicians, professors, etc. Cu- 
vier and Abercrombie stand at the head of the list, as re- 
gards the weight of the brain ; but above Webster and 
Dupuytren, are Ruloff, Fisk, an idiot, and a common labor- 
er. Far down in the list, is a celebrated mineralogist, whose 
brain, is at least six ounces below the average. The ad- 

1 JOHN JEFFRIES, An Account of the last Illness of the late Honourable Daniel 
Webster, American Journal of the Medical Sciences, Philadelphia, 1853, Xe\v 
Series, vol. xxv., p. 117, et seq. 

% CRUVEILHIER, Hcssox, BOUILLAUD, Froces-verbal de Touverture du corps df 
M. Dupuytren. Revue medicale^ Paris, 1835, tome i., p. 287. 

3 Loc. cit. 4 Loc. cit. 



350 NEKVOUS SYSTEM. 

vanced age of the person referred to, seventy-seven years, 
would not account for the small weight of the brain, though 
the weight is undoubtedly diminished in old persons. We 
are not surprised, then, in the tables based upon observa- 
tions of thousands of healthy brains of men not remarkable 
for great intellect, to find many between fifty-five and sixty 
ounces in weight. 

As the general result of all the observations upon the 
human subject, while we admit that intellectual vigor is in 
general coincident with large development of the cerebral 
hemispheres, there are certainly many striking exceptions to 
this rule when it is applied to individuals. 

Location of the Faculty of Articulate Language in a Re- 
stricted Portion of the Anterior Cerebral Lobes. Physiolo- 
gists are often slow to accept important facts bearing directly 
upon the functions of parts, drawn exclusively from pathol- 
ogy, especially when these facts are not capable of demon- 
stration by experiments upon the lower animals ; and per- 
haps this is due to a certain distrust of the accuracy of 
pathological researches as compared with the exact results 
of well-executed experimental observations. As regards the 
faculty of speech, however, our study must be Confined to 
man, the only animal capable of articulate language, and our 
data are drawn exclusively from pathology. Some physio- 
logical writers are still disposed to regard the location of 
the faculty of speech as not definitively settled ; but, from a 
careful study of the pathology of aphasia, we are convinced 
that there is no point in the physiology of the brain more 
exactly determined than that the faculty of speech is located 
in a well-defined and restricted portion of the anterior lobes. 
This is the more interesting and important, as it is the only 
sharply-defined faculty that has been accurately located in a 
distinct portion of the brain. 

"We do not propose to enter fully into the history of 
aphasia, as this belongs to pathology. In the companion- 



THE FACULTY OF ARTICULATE LANGUAGE. 351 

treatise to this volume, Hammond on the " Diseases of the 
Nervous System," the chapter on aphasia not only contains 
a full historical account of the disease, but is enriched by 
numerous original observations of the most striking char- 
acter. The profound acquirements of Dr. Hammond as a 
physiologist, and his skill as an original investigator in this 
department, lend additional weight to his deductions. In 
our references to the bibliography of the subject, we shall 
make use of the labors of Dr. Hammond, by whom the lit- 
erature has been exhaustively studied. 1 

Dr. Hammond states that " by aphasia is understood a 
condition produced by an affection of the brain by which the 
idea of language, or of its expression, is impaired." Certain 
cases of this disease present loss of speech because the sub- 
ject is incapable of coordinating the muscles used in articu- 
lation. The patient has a clear idea of language and of the 
meaning of words, and is able to write perfectly well. In 
other cases, the patient can neither speak nor express ideas 
in writing. In these, the idea of language is lost. In both 
of these varieties of the disease, the difficulty is either in the 
organ presiding over the faculty of speech or in the connec- 
tions of this organ with the muscles concerned in articula- 
tion. Thus regarded, aphasia does not include aphonia from 
laryngeal disease, or loss of speech such as is observed fre- 
quently in hysteria, in the insane, who sometimes refuse to 
speak from pure obstinacy, or in cases of paralysis of the 
parts immediately concerned in articulation. The whole 
history of the disease points to a particular part of the brain 
which presides over the faculty of speech. 

While we do not propose to treat of the history of apha- 
sia, we cannot refrain from quoting a case, detailed in 1T66, 
by Pourfour du Petit, which possesses great historical inter- 
est, as one of the first, if not the very first, in which the 
symptoms now recognized as aphasic were connected with 
disease of the left anterior cerebral lobe. "We quote this 

1 HAMMOND, Diseases of the Nervous System, Xew York, 1871, p. 166, et *eq. 
123 



352 NER7OU3 SYSTEM. 

case in full, because it seems to have escaped tlie attention 
of writers on aphasia : 

" Some time after I had made the experiments which I 
have just reported, a cavalryman of the garrison, aged thirty- 
five years, was brought into our hospital. He had been 
seized the day before with paralysis of the entire right side, 
which had occurred after a slight pleurisy, from which he 
had recovered ; he could move neither the arm, nor the right 
leg, nor could he maintain himself in his seat. The lower 
jaw was not distorted; he opened and closed the mouth 
with facility. He could move the tongue only with a great 
deal of difficulty, and could not protrude it from the mouth, 
nor pronounce any word. 

" The right eye seemed dimmed, and its sight was en- 
tirely lost, which I recognized, because, in presenting the 
finger, or a stick, very near this eye, he made no movement 
of the lid. But as soon as I touched the eye, he closed the 
lid. When I presented the finger or a stick to the left eye, 
he immediately closed it, though it was not touched. 

" He retained sensation on the paralyzed side as well as 
on the sound side. 

" A month after he had entered the hospital, he moved 
the tongue pretty easily, and even protruded it a little from 
the mouth, but he could pronounce nothing but non. 

"He was attacked with scurvy fifteen days after, and 
with abdominal flux, from which he died two months after 
his entrance into the hospital, not being relieved by any 
remedies. 

"His judgment was always perfectly normal during his 
disease, and he had no convulsive movements. 

" After death I removed the brain and spinal cord. I be- 
gan by dissecting the spinal cord, in which I found nothing 
abnormal, nor in the right side of the brain. But I found 
on the left side, the entire anterior protuberance which con- 
tains the internal and superior corpora striata (corps canneles\ 
the middle ,and the external or inferior, dissolved and con- 



THE FACULTY OF ARTICULATE LANGUAGE. 353 

verted into a substance resembling the lees of wine. It did 
not appear that this part had been swollen, and that it had 
become larger than natural. 

"Xeither the optic thalami nor the optic nerves were 
injured." 1 

The great interest of this case will appear when we come 
to note the connection between aphasia and the left anterior 
lobe of the cerebrum. 

As a preliminary to the location of the nerve-centre pre- 
siding exclusively over speech, it is necessary to establish the 
existence of the power of articulate language as a distinct 
faculty; and this is done by cases of disease in which this 
faculty seems to be lost, the general mental condition being 
unaffected. Passing over the passages in the writings of the 
ancients, in which it is stated that the power of speech is 
sometimes lost, and even some writers in the beginning of 
the present century, who connected this difficulty with lesions 
of the anterior lobes of the brain, we come to the observa- 
tions of Dr. Marc Dax, who, in 1836, read a paper before 
the medical congress at Montpellier, in which he showed im- 
pairment or loss of speech in one hundred and forty cases of 
right hemiplegia. Dax concluded, from these observations, 
that the faculty of articulate language occupies the left ante- 
rior lobe. This memoir, however, attracted but little atten- 
tion, until 1861, when the discussion was renewed by Broca ; 
and since then, Broca, Aubertin, Charcot, Falret, Perroud, 
and Trousseau, have reported numerous cases of aphasia 
with lesion of the left anterior lobe. In 1863, M. Gr. Dax, 
a son of Marc Dax, limited the lesion to the anterior and 
middle part of the left anterior lobe. It was further stated, 
by Broca and Hughlings Jackson, to be that portion of the 
orain nourished by the left middle cerebral artery. This 
subject has been more lately investigated by Sanders, Moxon, 
Ogle, Bateman, Bastian, Yon Benedict, Braunwart, and 

1 POCRFOUR DU PETIT, Fouveau si/steme du cervcau. Rccueil cT observation* 
d" anatomic et de chirurgie, Paris, 1766, p. 74. 



354: NERVOUS SYSTEM. 

by A. Flint, H. B. Wilbur, E. C. Seguin, and others, in 
this country. According to recent observers, the most fre- 
quent lesion in aphasia is in the parts supplied by the left 
middle cerebral artery, particularly the lobe of the insula, 
or the island of Reil ; and it is a curious fact that this part is 
found only in man and monkeys, being in the latter very 
slightly developed. While we must agree with Dr. Ham- 
mond in the statement that the organ of language cannot 
be absolutely restricted to these parts, it is none the less 
certain that they are most frequently the seat of lesion in 
aphasia. 

As illustrating the loss of the faculty of speech without 
any marked impairment of the intellectual faculties, we can 
cite numerous cases recorded by Dr. Hammond. A woman 
is described as presenting a countenance remarkably bright 
and cheerful, her whole expression being exceedingly intelli- 
gent. " She comprehends every word that is said to her, 
and attends to all her household duties. Yet she is unable 
to utter any words but ' no,' ' yes,' and ( dado.' " l Other 
cases are given, in which the intellect seemed to be clear, but 
in some, the faculty of speech was lost, and in others, both 
the faculty of speech and of writing. One case reported by 
Dr. Hammond is so striking that we give it in full : 

" The patient was a retired officer of the army, and con- 
sulted me in the autumn of 1869 for paralysis, vertigo, and 
slight difficulty of speaking, from which he had suffered for 
some months. Several years previously he had been under 
the care of my friend Dr. Metcalfe, for acute rheumatism, 
with cardiac complications. The history of the case pointed 
strongly to embolism, and, as the paralysis affected the right 
side, I diagnosticated a previous attack of embolism of the 
left middle cerebral artery. 

" The difficulty of speech was slight ; there were both 
amnesic and ataxic aphasia. 

" Under the treatment employed he improved very much 
1 Op. tit., p. 210. 



THE FACULTY OF ARTICULATE LANGUAGE. 355 

in the ability to walk, to use his arm, and to speak, so much 
so, that he and his friends considered him better than he 
had been for several years. But, about six weeks after he 
came under my charge, he had another attack. This time 
the left side was paralyzed, and there wa's no difficulty of 
speech. Galvanism was employed, as before, and he recov- 
ered sufficiently to go to Washington City. "While there, 
he had a third attack, characterized by right hemiplegia and 
aphasia. He soon recovered his power of speech, and soon 
afterward had a further attack, involving the left side, and 
unattended by aphasia. He recovered under the care of 
Dr. Basil Norris, of the army, and soon afterward came 
again to New York. A short time after his arrival I re- 
quested my friend Prof. Flint . to see him in consultation, 
with the special view of having him examine his heart. 
This was done with thoroughness, but no abnormal sounds 
were detected. While in New York he had two other at- 
tacks, during both of which he was delirious ; both were 
characterized by hemiplegia. That of the left side was un- 
accompanied by aberrations of language ; that of the right 
side was attended with ataxic and amnesic aphasia. He for- 
got the names of the most' ordinary things, and there were 
many words that he could not articulate at all. Thus, when 
he wanted a fan, lie called it c a large, flat thing, to make 
wind with.' He forgot my name, and could not pronounce 
the words beetle, general, physician, and many others. I 
sent him to Newport greatly improved, but he had other 
attacks there, and finally died in the autumn of the present 
year, of, I presume, cerebral softening. 

" The interesting features of this case are the concurrence 
of hemiplegia and ataxic and annesic aphasia, and the strik- 
ing fact that there was no aphasia when the paralysis in- 
volved the left side. Thus, according to my views of the 
case, the patient had repeated attacks of cerebral embolism. 
"When the embolus lodged in the left middle cerebral artery, 
there was aphasia accompanied by right hemiplegia ; when 



356 NERVOUS SYSTEM. 

the embolus obstructed the right middle cerebral artery, 
there was left hemiplegia, but no aphasia." 1 

An analysis of a large number of cases of aphasia re- 
corded by different observers shows that the great majority 
occur in connection with right hemiplegia. Dr. Hammond 
quotes 243 cases with, right, against 17 cases with left hemi- 
plegia. In cases verified by post-mortem examination, 514 
occurred when the lesion involved the left, and 31, when it 
involved the right anterior lobe. Dr. Hammond cites addi- 
tional cases, in 80 of \vhieh the lesion involved the left lobe, 
and in 2, the right lobe. 

While the above facts show that the cerebral lesion in 
aphasia involves the left anterior lobe in the great majority of 
cases, there are several instances in which the right lobe alone 
was affected ; and this has led physiologists and pathologists 
to deny the absolute location of the organ of language on the 
left side. Even if we reject a certain number of cases of 
aphasia with the brain-lesion limited to the right side, in 
w r hich we may suppose that the post-mortem examinations 
were incomplete, or the impairment of speech was due, per- 
haps, to simple paralysis of muscles, we must admit that, in 
a few instances, aphasia has followed injury or disease of the 
brain on the right side. Aside from the anatomical arrange- 
ment of the arteries, which seem to furnish the greater 
amount of blood to the left hemisphere, it is evident that, 
as far as voluntary movements are concerned, the right 
hand, foot, eye, etc., are used in preference to th/3 left ; and 
that the motor functions of the left hemisphere are superior 
in activity to those of the right. It would be interesting, 
then, to note the physical peculiarities of persons affected 
with left hemiplegia and aphasia. Dr. Bateman quotes two 
cases of aphasia dependent upon lesion of the right side of 
the brain and consequent left hemiplegia, in which the per- 
sons were left-handed ; a and these, few as they are, are in- 
teresting, as showing that a person may use the right side 

1 HAMMOND, op. cit., p. 215. " 2 BATEMAN, On Aphasia, London, 1870, p. 164. 



THE FACULTY OF ARTICULATE LANGUAGE. 357 

of the brain in speech, as in the other motor functions. In 
this connection, it may not be uninteresting to note that, 
although most anatomists have failed to find any marked 
difference in the weight of the two cerebral hemispheres, 
Dr. Boyd has shown by an " examination of nearly two hun- 
dred cases at St. Marylebone, in which the hemispheres were 
weighed separately, that almost invariably the weight of the 
left exceeded that of the right by at least the eighth of an 
ounce." 1 To conclude our citations of pathological facts bear- 
ing upon the location in the brain of the organ of speech, 
we may refer to an account, by Dr. Broadbent, of the brain 
of a deaf and dumb woman. In this case, the brain was 
found to be of about the usual weight, but the left third 
frontal convolution was of " comparatively small size and 
simple character." a 

Taking into consideration all of the pathological facts 
bearing upon the subject, it seems certain that, in the great 
majority of persons, the organ or part presiding over the 
faculty of articulate language is situated at or near the third 
frontal convolution and the island of Eeil in the left anterior 
lobe of the cerebrum, and mainly in the parts nourished by 
the middle cerebral artery. In some few instances, the or- 
gan seems to be located in the corresponding part on the 
right side. It is possible that, originally, both sides preside 
over speech, and the superiority of the left lobe of the brain 
over the right and its more constant use by preference in 
right-handed persons may lead to a gradual abolition of the 
functions of the right side of the brain, in connection with 
speech, simply from disuse. This view, however, is hypo- 
thetical, but is rendered probable by certain considerations, 
among the most important of which is the statement by 

1 BOTD, Table of the Weights of the Human Body and Internal Organs. 
Philosophical Transactions, London, 1861, vol. cli., part i., p. 261. 

2 BROADBEXT, On the Cerebral Convolutions of a Deaf and Dumb Woman. 
Journal of Anatomy and Physiology, Cambridge and London, 1870, vol. iv., p. 
225. 



358 NEKVOUS SYSTEM. 

Longet, that " one cerebral liemispliere in a healthy con- 
dition may suffice for the exercise of intelligence and the ex- 
ternal senses." In support of this statement, Longet cites 
several cases of serious injury of one hemisphere without 
impairment of the intellect. 1 

Another very important point, which we believe had 
never before been noted, is brought forward very strongly 
by Dr. Hammond. In what is called the ataxic form of 
aphasia, the idea and memory of words are intact, and there 
is simply loss of speech from inability to coordinate the mus- 
cles concerned in articulate language. Patients affected in 
this way cannot speak, but can write with ease and correct- 
ness. In the amnesic form of the disease, the idea and 
memory of language are lost ; patients cannot speak, and are 
affected with agraphia, or inability to write. In cases in 
which hemiplegia is marked, the aphasia is of the ataxic 
form ; while in cases in which there is no hemiplegia, the 
aphasia is amnesic. 

" The gray matter of the lobes presides over the idea of 
language, and hence over the memory of words. When it 
only is involved, there is no hemiplegia, and there is no dif- 
ficulty of articulation. The trouble is altogether as regards 
the memory of words. 

66 The corpus striatum contains the fibres which come from 
the anterior column of the spinal cord, and is besides con- 
nected wuth the hemisphere. A lesion, therefore, of this 
ganglion, or other part of the motor tract, causes paralysis 
of motion on the opposite side of the body. The cases I 
have detailed show, without exception, that the power of 
coordinating the muscles of speech is directly associated 
with this hemiplegia. A lesion, therefore, followed by hemi- 
plegia and ataxic aphasia, indicates the motor tract as the 
seat. If amnesic aphasia is also present, the hemisphere is 
ikewise involved." a 

1 LONGET, Anatomic et physiologic du systeme nerveux, Paris, 1842, tome i., p. 
666, et seq. 2 HAMMOND, op. cit., p. 217. 



CHAPTER XIII. 

THE CEREBELLUM. 

Some points in the physiological anatomy of the cerebellum Course of the 
fibres in the cerebellum General properties of the cerebellum Functions 
of the cerebellum Extirpation of the cerebellum in animals Incomplete 
extirpation of the cerebellum Pathological facts bearing upon the func- 
tions of the cerebellum Andrei's cases Other cases of disease of the 
cerebellum Connection of the cerebellum with the generative function 
Development of the cerebellum in the lower animals Paralysis from disease 
or injury of the cerebellum. 

IT is not necessary, in order to comprehend the functions 
of the cerebellum, as far as these are known, to enter into a 
full description of its anatomical characters. The points, in 
this connection, that are most interesting to us as physiolo- 
gists are, the division of the substance of the cerebellum into 
gray and white matter ; the connection between the cells 
and fibres ; the connection of the fibres with the cerebrum, 
and with the prolongations of the columns of the spinal 
cord ; and the passage of fibres between the two lateral 
lobes. These points, therefore, will be the only ones that 
will engage our attention. 



o o 



Some Points in the Physiological Anatomy of the Cere- 
bellum. 

As we have seen, in treating of the general arrangement 
of the encephalon, the cerebellum, situated beneath the pos- 
terior lobes of the cerebrum, weighs about 5*20 ounces av. 
in the male, and 4- TO ounces in the female. The propor- 



360 NEKVOUS SYSTEM. 

tionate weight to that of the cerebrum is as 1 to 8-f- in the 
male, and as 1 to 8J in the female. It is separated from the 
cerebrum by a strong process of the dura mater, called the 
tentorium. Like the cerebrum, the cerebellum presents an 
external layer of gray matter, the interior being formed of 
white, or fibrous nerve-tissue. The amount of the gray sub- 
stance is very much increased by numerous fine convolu- 
tions, and is farther extended by the penetration, from the 
surface, of arborescent processes of gray matter. Near the 
centre of each lateral lobe, embedded in the white substance, 
is an irregularly dentated mass of cellular matter, called the 
corpus dentatum. The cerebellar convolutions are more 
numerous, and the gray substance is deeper, than in the 
cerebrum ; and these convolutions are present in many of 
the inferior animals in which the surface of the cerebrum is 
smooth. 

The cerebellum consists of two lateral hemispheres, more 
largely developed in man than in the inferior animals, and a 
median lobe. The hemispheres are subdivided into smaller 
lobes, which it is unnecessary to describe. Beneath the 
cerebellum, bounded in front and below by the medulla 
oblongata and pons, laterally by the superior peduncles, and 
superiorly by the cerebellum itself, is a lozenge-shaped 
cavity, called the fourth ventricle. The crura, or peduncles 
will be described in connection with the direction of the 
fibres. 

The structure of the gray substance of the convolutions 
presents certain peculiarities. This portion is divided quite 
distinctly into an internal and an external layer. The inter- 
nal layer presents an exceedingly delicate net-work of fine 
nerve-fibres, which pass to the cells of the external layer. 
In the plexus of anastomosing fibres, are found numer- 
ous bodies like free nuclei, called by Robin, myelocytes. 
The external layer is somewhat like the external layer of gray 
substance on the posterior lobes of the cerebrum } and is 
more or less sharply divided into two or more secondary 



COURSE OF THE FIBRES IX THE CEREEELLOI. 361 

layers. The most external portion of tins layer contains a 
few small nerve-cells and fine filaments of connective tissue ; 
and the rest of the layer contains a great number of large 
cells, rounded or ovoid, with two or three, and sometimes, 
though rarely, four prolongations. 1 The mode of connection 
between the nerve-cells and the fibres has already been de- 
scribed under the head of the general structure of the nervous 
system. 2 

Course of the Fibres in the Cerebellum. Most anatomical 
writers give a very simple description of the course of the 
nerve-fibres in the cerebellum. From the gray substance 
of the convolutions and their prolongations, the fibres con- 
verge to form finally the three crura, or peduncles on each 
side. The superior peduncles pass forward and upward to 
the crura cerebri and the optic thalami. These connect the 
cerebellum with the cerebrum. Beneath the tubercular quad- 
rigemina, some of these fibres decussate with the corre- 
sponding fibres upon the opposite side ; so that certain of 
the fibres of the superior peduncles pass to the corresponding 
side of the cerebrum, and others pass to the cerebral hemi- 
sphere of the opposite side. 

The middle peduncles arise from the lateral hemispheres 
of the cerebellum, pass to the pons Yarolii, where they de- 
cussate, connecting together the two sides of the cerebellum. 

The inferior peduncles pass to the medulla oblongata, 
and are continuous with the restiform bodies, which, in turn, 
are continuations chiefly of the posterior columns of the 
spinal cord. 

According to Luys, the fibres from the cortical substance 
of the cerebellum all pass to the corpora dentata and there 
terminate, being connected with the cells. From the cor- 
pora dentata, new fibres arise, which go to form the cerebel- 
lar peduncles. Luys does not admit the existence of com- 

1 KOLLIKEI^ Elements tfhistologie humaine, Paris, 1868, p. 387, et seq. 
9 See page 50. 



362 NERVOUS SYSTEM. 

missural fibres connecting the two lateral halves of the 
cerebellum, and assumes that the decussation between the 
two sides takes place through a special system of decussating 
prolongations from the cells of the cortical substance, which 
he calls " intercortical commissural fibres." 1 This view, 
however, is not adopted by the best anatomists ; but nearly 
all agree that new fibres arise from the cells of the corpora 
dentata and contribute to the formation of the peduncles. 

From the above sketch, the physiological significance of 
the direction of the fibres, as appears from the most reliable 
and generally-accepted anatomical investigations, is suffi- 
ciently evident. By the superior peduncles, the cerebellum 
is connected, as are all of the encephalic ganglia, with the 
cerebrum ; by the middle peduncles, the two lateral halves 
of the cerebellum are intimately connected with each other ; 
and by the inferior peduncles, the cerebellum is connected 
with the posterior columns of the spinal cord. "We shall 
see, when we come to study the functions of the cerebellum, 
that its connection with the posterior white columns of the 
cord is a point of great interest and importance. 

General Properties of the Cerebellum. There is now 
no difference of opinion among physiologists, with regard to 
the general properties of the cerebellum. We may safely 
discard the observations of Zinn and Haller upon this point, 
for these experimenters, who conceived that irritation of the 
cerebellum produced convulsive movements, 2 undoubtedly 
stimulated portions of the medulla oblongata ; at least, this 
must be assumed, if we accept the results of the more recent 
experiments of Flourens, Longet, and many others. Flou- 
rens, who made the first elaborate and entirely satisfactory 
observations upon the cerebellum in living animals, noted, 

1 LUYS, Recherchcs sur le systeme nerveux cerebro-spinal, Paris, 1865, p. 126, 
*t *eq. 

2 HALLER, Memoires sur la nature sensible et irritable des parties du corps 
animal, Lausanne, 1756, p. 208. 



FUNCTIONS ,OF THE CEREBELLUM. 363 

ji all of his experiments, that lesion or irritation of the cere- 
bellum alone produced neither pain nor convulsions ; * and 
the same results have followed the observations of Longet 3 
and of all modern physiologists who have investigated this 
question practically. We have ourselves frequently exposed 
and mutilated the cerebellum in pigeons, and have never 
observed any evidence of excitability or sensibility. From 
these facts, we must conclude that the cerebellum is inex- 
citable and insensible to direct stimulation, at least as far as 
has been shown by direct observations. It is not impossi- 
ble, however, that future experiments may reverse this gen- 
erally-received opinion ; particularly in view of the recent ob- 
servations of Fritsch and Hitzig, already cited, 3 which show 
that certain parts of the cerebrum are excitable, and that the 
excitability of the encephalic centres rapidly disappears in 
living animals, as the result of pain and haemorrhage. We 
should note, also, the experiments of Budge, who observed 
movements in the testicles and vasa deferentia, in males, and 
in the cornua of the uterus and the Fallopian tubes, in 
females, following irritation of the cerebellum. 4 Hammond 
noted movements of this kind in cats just killed, and also 
movements of the intestines and of the muscles of the ab- 
domen, thigh, and back. 5 

Functions of the Cerebellum. 

There are still the widest differences of opinion among 
physiologists, w r ith regard to the functions of the cerebellum, 
mainly for the reason that the experiments upon the lower 

1 FLOURENS, Recherches experimentales sur les proprietes et les functions du sys- 
teme nerveux, Paris, 1842, p. 18. 

li LONGET, Anatomic et physiologie.du systeme nerveux, Paris, 1842, tome i., pp. 
783, 734. 

3 See page 323. 

4 BUDGE, Lehrbuch der specietten Physiologic des Menschen^. Leipzig, 1862, S. 
788. 

5 HAMMOND, Physiology and Patludogy of the Cerebellum. Quarterly Journal 
of Psychological Medicine^ New York, 1869, vol. iii., p. 223. 



364: NESVOUS SYSTEM. 

animals, made by Floumis and his followers, though in 
themselves sufficiently definite, are apparently contradicted 
by pathological observations upon the human subject. There 
should be no such discrepancy between well-conducted ex- 
periments and carefully-observed cases of disease or injury ; 
for it is certain that the functions of the cerebellum present no 
essential differences in different animals, at least in man, the 
mammalia, and birds. It is necessary, therefore, for the phy- 
siologist, by carefully analyzing and correcting the results 
obtained by direct experimentation, and by applying to the 
study of palological observations the facts elicited by these 
experiments, to endeavor to harmonize the real or apparent 
contradictions 5 for, as we have often had occasion to remark, 
there are no exceptions to the laws to which the functions 
of similar classes of animals are subordinated ; and observa- 
tions and experiments, apparently discordant, will always be 
found, as our positive knowledge advances, to present differ- 
ences in the conditions under which the phenomena have 
been observed. To apply this to the functions of the cere- 
bellum, it may be safely assumed that it is impossible for 
this organ to preside directly and exclusively over the mus- 
cular coordination in birds and the inferior mammals, and 
in man, to possess different functions. "With regard to the 
cerebrum, man possesses, not only a higher degree of de- 
velopment of certain intellectual faculties than the inferior 
animals, but is endowed with others, such as the power of 
articulate language. But in man and in the higher orders 
of animals, the general properties and functions of the mus- 
cular system are essentially the same. To take one of the 
most generally-accepted views of the functions of the cere- 
bellum, if this be the centre for muscular coordination in 
birds and mammals, it has the same office in man, though 
it may possess additional functions not found lower in the 
scale of animal life. Keeping in view, then, the desirability 
of bringing into accord the results of experiments and of 
pathological observations, we will first study carefully the 



FUNCTIONS -OF THE CEREBELLUM. 365 

phenomena which follow injury or extirpation ,of the cere- 
bellum in animals. 

Extirpation of the Cerebellum in Animals. In birds, 
and in certain mammals in which the operation has been 
successful, the more or less complete extirpation of the cere- 
bellum is followed by well-marked phenomena, presenting 
always the same character, but somewhat differently inter- 
preted by various experimenters. Experiments of this kind 
were first made by Flourens ; and the accuracy of his obser- 
vations has never been successfully controverted, whatever 
may have been said of his physiological deductions. In- 
deed, there are few if any important points in the phenom- 
ena following partial or complete removal of the cerebellum 
that escaped the attention of this most accurate observer. 

Laying aside, for the present, the deductions to be made 
from experiments on animals, the phenomena noted by Flou- 
rens and by all who have repeated his observations on the 
cerebellum are as follows : 

" I extirpated the cerebellum by successive layers in a 
pigeon. During the removal of the first layers, there only 
appeared slight feebleness and want of harmony in ^the 
movements. 

" At the middle layers, there was manifested an almost 
universal agitation, although there was not added any sign 
of convulsion ; the animal executed sudden and disordered 
movements ; it heard and saw. 

" On the removal of the last layers, the animal, the facul- 
ty of jumping, flying, walking, and maintaining the erect 
position being more and more disturbed by the preceding 
mutilations, lost this faculty entirely. 

" Placed on the back, it was not able to recover itself. 
Far from resting calm and steady, as occurs in pigeons de- 
prived of the cerebral lobes, it became vainly and continually 
agitated, but it never moved in a firm and definite manner. 

" For example, it saw a blow with which it was threatened, 



366 NERVOUS SYSTEM. 

wished to avoid it, made a thousand efforts to avoid it, but 
did not succeed. If it were placed on its back, it would not 
rest, exhausted itself in vain efforts to get up, and finished 
by remaining in that position in spite of itself. 

" Finally, volition, sensation, perception, persisted ; the 
possibility of making general movements persisted also ; but 
the coordination of the movements in regular and definite 
acts of locomotion was lost." ] 

These are the phenomena observed after total extirpation 
of the cerebellum. Voluntary movement, sensation, general 
sensibility, and the special senses, seem to be intact ; but 
there is always a loss of the power of equilibrium, and the 
movements executed are never regular, efficient and coor- 
dinate. Flourens farther states that animals operated upon 
in this way retain the intellectual and perceptive faculties. 11 

It is exceedingly important now to note the effects of 
partial removal of the cerebellum, as these bear directly upon 
cases of disease or injury of this organ in the human subject, 
in which its disorganization is very rarely complete. We 
may illustrate this also by citing two of Flourens's typical 
experiments : 

" I. I removed by successive layers, all of the upper half 
of the cerebellum in a young cock. 

" The animal immediately lost all stability, all regularity 
in its movements; and its tottering and ~bizarre mode of 
progression reminded one entirely of the gait in alcoholic 
intoxication. 

" Four days after, the equilibrium was less disturbed, and 
the progression was more firm and assured. 

" Fifteen days after, the equilibrium was completely re- 
stored. 

"II. I removed, in a pigeon, about the half of the cere- 
bellum ; and I removed this organ completely in a fowl. 

1 FLOURENS, Reckerches cxperimentales sur les proprietes et les fonctions du sys- 
time nerveux, Paris, 1842, p. 37. 
8 Op. ci'., p. 134. 



FUNCTIONS OF THE CEREBELLUM. 367 

" At the end of a certain time, the pigeon had regained 
its equilibrium ; the fowl did not regain it at all : the latter 
lived nevertheless for more than four months after the opera- 
tion." ' 

These important observations we have repeatedly con- 
firmed, and have in our possession the encephalon of a pigeon 
which recovered completely after removal of about two-thirds 
of the cerebellum, the animal first presenting marked defi- 
ciency in coordinating power. 

Such are the phenomena observed in experiments upon 
the cerebellum in birds, and they have been extended by 
Flourens a and others 3 to certain mammals, as young cats, 
dogs, moles, 'mice, etc. Our own experiments, which have 
been very numerous during the last twelve years, are simply 
repetitions of those of Flourens, and the results have been 
the same without exception. 

The only difficulties in operating upon the cerebellum 
arise from haemorrhage and the danger of injuring the 
medulla oblongata. The skull is exposed by slitting up the 
scalp, and the calvarium is removed in its posterior portion, 
penetrating just above the upper insertion of the cervical 
muscles. It is well to leave a strip of bone in the median 
line, thereby avoiding haemorrhage from the great venous 
sinus, though this is not essential. The cerebellum is thus 
exposed, and may be removed in part or entirely, by a deli- 
cate scalpel or forceps, when the characteristic phenomena 
just described are observed. Animals operated upon in this 
way feel the sense of hunger and attempt to eat, but when 
the movements are very irregular, they are unable to take 
food. We have frequently compared the phenomena pre- 
sented after removal of the cerebellum with the movements 
of a pigeon intoxicated by forcing down the oesophagus a 

1 FLOUREXS, op. cit., p. 102. 
8 Op. cit., p. 138, et seq. 

8 YULPIAX, Lemons sur la physiologic generate et compared du systeme ner- 
veux, Paris, 1866, p. 606. 
124 



368 NERVOUS SYSTEM. 

little bread impregnated with alcohol, and they present a 
striking similarity. 

In view of the remarkable uniformity in the actual results 
obtained by different experimenters, it is hardly necessary to 
cite all of the observations made upon the lower animals. 
The phenomena observed by Flourens have been in the main 
confirmed by Fodera, 1 Bouillaud, 2 Magendie, 3 Wagner, 4 Lus- 
sana, 5 Hammond, 6 Dalton, 7 Yulpian, 8 Mitchell, 9 Onimus, 10 
and many others. Certain of these authors differ from Flou- 
rens in their ideas concerning the functions of the cerebel- 
lum, while they admit the accuracy of his observations. 

We will eliminate from the present discussion the experi- 
ments made upon animals low in the scale, such as frogs and 
fishes, though in some of these, the results are in accord with 
the observations just cited upon birds and mammals, 11 and 
confine ourselves to an interpretation of the phenomena ob- 
served after extirpation of the cerebellum in animals in which 
the muscular and nervous arrangement is like that of the 

I FODERA, Rechcrches experimentales sur le systeme nerveux. Journal de 
physiologic, Paris, 1823, tome iii., p. 193. 

* BOUILLAUD, Recherches experimentales tendant d prouver qne le cerveht preside 
aux actes de la station et de la progression. Archives generales de medecine, Paris, 
1827, tome xv., p. 68, et seq. 

3 MAGENDIE, Precis eleinentaire de physiologie, Paris, 1836, tome i., p. 
409. 

4 WAGNER, Recherches critiques et experimentales svr les fonctions du cerveau. 
Journal de la physiologie, Paris, 1861, tome iv., p. 258. 

5 LUSSANA, Leconn sur les fonctions du cervelet. Journal de la physiologic, 
Paris, 1862, tome v., p. 418. 

6 HAMMOND, The Physiology and Pathology of the Cerebellum. Quarterly 
Journal of Psychological Medicine, New York, 1869, vol. iii., p. 230. 

7 DALTON, Human Physiology, Philadelphia, 1871, p. 445. 

8 VULPIAN, Systeme nerveux, Paris, 1866, p. 618. 

9 S. WEIR MITCHELL, Researches on the Physiology of the Cerebellum. Ameri- 
can Journal of the Medical Sciences, Philadelphia, 1869, New Series, No. cxiv., p. 
331. 

10 ONIMCS, Recherches experimentales, etc. Journal de I'anafomie, Paris, 1870- 
1871, tome vii., p. 652, et seq. Onimus believes that the cerebellum presides 
over equilibration rather than general muscular coordination. 

II VULPIAN, op. cit., p. 689. 



FUNCTIONS OF THE CEREBELLUM. 369 

human subject. The results of this mutilation are as defi- 
nite, distinct, and invariable", as in any experiments on living 
animals, and, taken by themselves, lead inevitably to but 
one conclusion. 

AVhen the greatest part or the whole of the cerebellum is 
removed from a bird or mammal, the animal being, before 
the operation, in a perfectly normal condition, and no other 
parts being injured, there are no phenomena constantly and 
invariably observed except certain modifications of the volun- 
tary movements. The intelligence, general and special sen- 
sibility, the involuntary movements, and the simple faculty 
of voluntary motion, remain. The movements are always 
exceedingly irregular and incoordinate ; the animal cannot 
maintain its equilibrium ; and, on account of the impossibil- 
ity of making regular movements, it cannot feed. This want 
of equilibrium and of the power of coordinating the muscles 
of the general voluntary system causes the animal to assume 
the most absurd and remarkable postures, which, to one ac- 
customed to these experiments, are entirely characteristic. 
Call this want of equilibration, of coordination, of " muscular 
sense," an indication of vertigo, or what we will, the fact 
remains, that regular and coordinate muscular action in 
standing, walking, or flying, is impossible, although volun- 
tary power remain. It is well known that many muscular 
acts are more or less automatic, as in standing, and, to a cer- 
tain extent, in walking. These acts, as well as nearly all 
voluntary movements, require a certain coordination of the 
muscles, and this, and this alone, is abolished by extirpation 
of the cerebellum. It is true that destruction of the spiral 
canals of the internal ear produces analogous disorders of 
movement, 1 but this is the only mutilation, except division 

1 FLOUREXS, Recherches experimentales sur les proprietes et les functions du 
tysteme nerveux, Paris, 1842, p. 446. 

GOLTZ, Ueber die physiologische Bedeutung der Bogengdnge des Ohrlabyrinths. 
Archivfiir die gesamtnte Physiologic, Bonn, 1870, Bd. Hi., S. 172, et seq. 

Taking the results of his experiments as a basis, Goltz proposes the theory 
that the semicircular canals are the organs presiding over the sense of equilib- 



370 NEKVOUS SYSTEM. 

of the anterior white columns of the cord, which produces 
any thing like the results of cerebellar injury. Certain im- 
portant coordinate muscular movements are well known to 
be dependent upon distinct nerve-centres. The acts of res- 
piration are presided over exclusively by the medulla oblon- 
gata. Deglutition probably has its distinct nerve-centre, as 
well as the movements of the eyes. The centre regulating 
the coordinate movements in speech is situated in the an- 
terior cerebral lobes. None of these peculiar movements 
are affected by extirpation of the cerebellum. 

If there be a distinct nerve-centre which presides over 
the coordination of the general voluntary movements, ex- 
periments upon the higher classes of animals show that this 
centre is located in the cerebellum. It may be either in the 
entire cerebellum or in a certain portion of this organ, but 
if it be confined to a restricted part, this has not yet been 
determined. If the cerebellum preside over coordination, 
as a physiological necessity, the centre must be connected 
by nerves with the general muscular system. If this con- 
nection exist, a complete interruption of the avenue of com- 
munication between the cerebellum and the muscles, we 
would naturally expect, would be followed by loss of coor- 
dinating power. From the anatomical connections of the 
cerebellum, it appears that the only communication be- 
tween this 'Organ and the general system is through the 
posterior white columns of the spinal cord. TVe have seen 
that these columns are not for the transmission of the gen- 
eral sensory impressions, and there is no satisfactory evi- 
dence that they convey to the encephalon the so-called mus- 
cular sense. As regards general sensibility and voluntary 
motion, we cannot ascribe any function to the posterior 

rium of the head, and thereby of the whole body ; that the pressure of the liquid 
in these canals varies with the movements of the head, and that the brain re- 
ceives from these, information with regard to the position of the head, and is 
able to regulate the general movements accordingly ; and that this information 
is inaccurate when the pressure of liquid in the canals is abnormal, the result 
being disturbance of the general equilibrium. 



FUNCTIONS OF THE CEREBELLUM. 371 

white columns, except that when they are divided at several 
points, we invariably have want of coordination in the gen- 
eral muscular system. 1 Whpn the posterior white columns 
are disorganized in the human subject, we have loss or im- 
pairment of coordinating power, even though the general 
sensibility be not affected, as in the disease called locomotor 
ataxia. 

Confining ourselves still to the interpretation of experi- 
ments upon living animals, and leaving for subsequent con- 
sideration the phenomena observed in cases of disease or 
injury of the cerebellum in the human subject, we are led 
to the following conclusions : 

There is a necessity for coordination of the movements 
of the general voluntary system of muscles, by means of a 
nerve-centre or centres. 

Whatever other functions the cerebellum may have, it 
acts as the centre presiding over equilibration and general 
muscular coordination. 

The cerebellum has its nervous connection with the gen- 
eral muscular system through the posterior white columns 
of the spinal cord, a fact which is capable both of anatomical 
and physiological demonstration. 

If the cerebellum be extirpated, there is loss of coordi- 
nating power ; and if the posterior white columns of the 
cord be completely divided, destroying the communication 
between the cerebellum and the general system, there is 
also loss of coordinating power. 

When a small portion only of the cerebellum is removed, 
there is slight disturbance of coordination, and the disor- 
dered movements are marked in proportion to the extent of 
injury to the cerebellum. 

After extirpation of even one-half or two-thirds of the 
cerebellum, the disturbances in coordination immediately 

1 The reader is advised to study, in this connection, that portion of the 
chapter on the spinal cord as a conductor, which treats of the probable func- 
tions of the posterior white columns (see page 289). 



372 NERVOUS SYSTEM. 

following the operation may disappear, and the animal may 
entirely recover, without any regeneration of the extirpated 
nerve-substance. This important fact enables us to under- 
stand how, in certain cases of disease of the cerebellum in 
the human subject, when the disorganization of the nerve- 
tissue is slow and gradual, there may never be any disorder 
in the movements. 

We present the above conclusions, as in our own mind 
positive and definite. It is proper to state, however, that 
the definition of the function of the cerebellum is one of the 
points stated by most physiological authors as doubtful and 
unsettled ; and this is so, mainly because many writers have 
been unable to harmonize, the experimental facts above de- 
tailed, with cases 6f disease or injury of the cerebellum in 
the human subject. We conceive that this has frequently 
been due to an imperfect study of the pathological facts, 
which we now propose to investigate as thoroughly as pos- 
sible. 

Pathological Facts bearing upon the Functions of the 
Cerebellum. Nearly all writers on the physiology of the 
nervous system, while they agree that extirpation of the 
cerebellum in the lower animals produces irregularity of 
movements, are arrested, as it were, in their deductions, by 
the following quotation from Andral, in his report of ninety- 
three cases of disease of the cerebellum : 

." A more remarkable alteration of movement is noted 
in the observation of M. Lallemand. The patient staggered 
on his legs, and often came near falling forward. In this 
case, the only one which tends to confirm the opinion of 
physiologists who regard the cerebellum as the organ of 
the coordination of movements, the cerebellum was entirely 
transformed into a sac filled with pus." 1 

1 ANDRAL, Clinique medicale, Bruxelles, 1834, tome v., p. 501. 
The case alluded to is quoted from Lallemand, which we have consulted in 
the original, and will refer to again. 



FUNCTIONS OF THE CEKEBELLTJM. 373 

The bare statement, such as is generally made, that An- 
dral collected ninety-three cases of disease of the cerebellum, 
only one of which tends to show that this is the organ of 
muscular coordination, is sufficient to arrest any physiologist 
in the conclusions that would naturally be drawn from ex- 
perimental facts ; and nearly all writers have expressed them- 
selves as uncertain upon the question of the function of the 
cerebellum. Before we go any farther, we wish to settle, 
once for all, the physiological bearing of these cases ; and, 
with this end in view, have carefully studied, analyzed, and 
tabulated them. Out of the ninety-three cases, fifteen were 
observed by Andral, and seventy-eight are quoted from 
various authors. An analysis of these cases, with reference 
to conditions likely to complicate the effects of the cerebellar 
disease, etc., is given in the following table : 

Analysis of AndrdUs ninety-three Cases of Disease of the 

Cerebellum. 
(Six Cases, observed ~by Andral.) 

Hemiplegia; death in fifty hours . . . . . .1 case. 

Hemiplegia ; sudden death 1 " 

Hemiplegia ; death hi two days 1 " 

Hemiplegia ; associated with cerebral haemorrhage . . . 3 6 l cases. 

(Seventy -eight Cases, quoted from various Authors.) 

Haemorrhage into the cerebellum ; quoted from Serres . . 6 * cases. 

quoted from Dance . -If case - 

" " " quoted from Bayle . . 1 j u 
" " " quoted from Guiot . . 1 " ' 
" " " (Serres) hemiplegia . . 2 cases. 
" " " (Cazes) coma ... 1 case. 
" (Morgagni) ; found dead . 1 " 
" " " (Sedillot) ; died in fifteen min- 
utes . . . . 1 " 
(Cafford); died suddenly . 1 " 
Haemorrhage (Michelet) ; apoplexy two years before death ; found 

an old clot in the right lobe of the cerebellum . . . 1 " 

16 cases. 

1 In these six cases, there was haemorrhage into the cerebellum. 



374: 



NERVOUS SYSTEM. 



Brought forward 16 cases 

Haemorrhage (quoted from various authors) ; haemorrhage into 

the cerebrum as well as the cerebellum . . . . 9 " 

Atrophy of the left cerebral and the right cerebellar hemisphere 2 " 

Cases of disease, with paralysis ; quoted from various authors . 9 " 

Cases of abscess, with paralysis ; quoted from various authors . 3 " 

Cyst (Recamier) ; convulsions 1 case. 

Abscess (Laugier) ; convulsions 1 " 

Abscess, involving the entire cerebellum (Lallemand) ; want of 

coordination 1 . . . . 1 " 

Cases, quoted from various authors, in which no disturbance was 

noted in the movements ; the disease was confined to one 

lateral lobe of the cerebellum 5 cases. 

Cases of tumor, quoted from various authors, in which there 

was paralysis 15 " 

Cases of tumor, associated with disease of the cerebrum . . 7 ** 
Cases of tumor, associated with convulsions ; the descriptions 

are very indefinite 9 78 cases 

(Nine Cases, observed ~by Andral.) 

Softening ; herniptegia and convulsions 1 case. 

Softening ; hemiplegia and subsequent haemorrhage . . . 1 " 

Softening ; hemiplegia and haemorrhage 1 " 

Softening ; agitation, like convulsions, of the members . . 1 " 

Cyst ; paralysis and convulsions 1 " 

Tubercle; hemiplegia ( 1 " 

Five small tubercles in one hemisphere of the cerebellum ; move- 
ments normal 1 " 

Tuberculous mass, the size of a hazel-nut, on one side of the 

cerebellum ; movements normal 1 " 

Cyst, the size of a hazel-nut, on one side of the cerebellum; 

movements normal 1 9 cases. 

Add cases of haemorrhage, previously cited, observed by Andral, 6 " 

Add cases quoted from various authors 73 " 

Total cases collected by Andral 2 . . 93 cases. 

In six cases, quoted from Serres, marked *, " there were 
observed all the signs of violent apoplexy ; nothing in par- 
ticular is said with regard to disorders of movement " (An- 
dral, op. cit., p. 475). In the case quoted from Dance, 

1 This is the single case, noted by Andral, out of the ninety-three, showing 
want of coordination. 

2 ANDRAL, Clinique medicale, Bruxelles, 1834, tome v., p. 468, et seq. 



FUNCTIONS -OF THE CEREBELLUM. 375 

marked f? the patient was struck with apoplexy (Andral, 
op. tit., p. 475). In the case quoted -from Bayle, marked J, 
the patient suddenly lost consciousness, had convulsive move- 
ments on the third day, and died in coma, on the fifth day 
(Andral, op. cit., p. 476). In the case quoted from Guiot, 
marked , there was " no lesion except effusion of blood in 
the median lobe of the cerebellum. The individual who was 
the subject of this observation had had an attack of apo- 
plexy. Before his attack, he had for some tune a tottering 
gait (demarche chancelante), and, after the attack, remained 
hemiplegic on the right side " (Andral, op. tit., p. 476). 

Let us now carefully review these ninety-three cases of 
Andral, which have been hold in terror em over those who 
have ventured to argue, from experiments on animals, that 
the cerebellum is the coordinator of the muscular movements, 
and see how many may properly be thrown out of the ques- 
tion ! 

"We can discard the first six cases, observed by Andral, in 
which there was hemiplegia, speedy death, and in three of 
which, there was cerebral haemorrhage ; for we could hardly 
observe want of coordination in hemiplegics or in cases 
complicated with cerebral disease. "We can discard the six 
cases, quoted from Serres, in which there was violent apo- 
plexy, as well as the case quoted from Dance, with apoplexy 
and the case quoted from Bayle, with coma and convulsions. 
It is evident that these cases are useless in noting the pres- 
ence or absence of coordinating power. "We can discard two 
cases (Serres) with hemiplegia ; one (Cazes) with coma ; one, 
(Morgagni) found dead ; one (Sedillot) died in fifteen min- 
utes ; one (Cafford) died suddenly ; one (Michelet) apoplexy 
two years before death, and an old clot in the right lobe 
of the cerebellum. This last case is in accord with experi- 
ments on animals ; for we have seen that the coordinating 
power may be restored after loss of one-half of the cerebel- 
lum. "We can discard nine cases quoted from various authors, 
in which there was cerebral as well as cerebellar haemor- 



376 NERVOUS SYSTEM. 

rhage ; two cases of paralysis, with atrophy of one hemi 
sphere of the cerebrum and one hemisphere of the cerebel- 
lum ; nine indefinitely described cases, with paralysis ; three 
cases of abscess, with paralysis ; one case of cyst and one of 
abscess, with paralysis ; fifteen cases of tumor, with paraly- 
sis ; seven cases, associated with disease of the cerebrum and 
paralysis ; nine very indefinitely described cases, associated 
with convulsions. Of the remaining cases observed by An- 
dral, we can discard one, with hemiplegia and convulsions ; 
one, with hemiplegia and subsequent haemorrhage ; one, 
with hemiplegia ; one case of cyst, with paralysis and con- 
vulsions ; one, of tubercle, with hemiplegia. We can also 
discard one case of five small tubercles in one hemisphere 
of the cerebellum ; one, of a tuberculous mass, the size of a 
hazel-nut, on one side ; one, of a cyst, the size of a hazel- 
nut, on one side. These last cases do not present sufficient 
destruction of the cerebellar substance to lead us to expect 
any disorder in the movements. 

Thus far we have discarded eighty-five cases, leaving 
eight to be analyzed. Of these eight cases, in five, it is 
simply stated that the movements were unaffected, and that 
" one of the lateral lobes of the cerebellum was the seat of 
abscess " (Andral, op. cit., p. 500). In view of this bare state- 
ment, and the fact that, in animals, recovery of coordinating 
power takes place when half of the cerebellum has been 
removed, we may throw out these cases as incomplete. It 
must be remembered that the abscesses were probably of 
slow development ; and if they did not destroy a sufficiently 
large portion of the cerebellum to influence the coordinating 
power permanently, it is not probable that the functions of 
this organ would be at all affected, as there would be no 
shock, as in the sudden removal of substance by an operation. 

We are thus reduced to three cases ; and in all of these, 
the movements were more or less affected. These cases we 
will now study as closely as is possible from the details given. 

CASE I. The first case is quoted from Guiot. There was 



FUNCTIONS, OF THE CEKEBELLUM. 377 

no lesion, except an effusion of blood in the median lobe of 
the cerebellum, and there was probably no pressure upon 
the peduncles. " The individual who was the subject of this 
observation had had an attack of apoplexy. Before the at- 
tack, he had for some time a staggering gait (une demarche 
chancelante), and, after the attack, he had remained liemi- 
plegic on the left side" (Andral, op. tit., p. 476). From 
these meagre details, it seems probable that there was a cer- 
tain amount of difficulty of coordination, though the descrip- 
tion is not as definite as could be desired. 

CASE II. The second case was observed by Andral. A 
groom, not quite forty years of age, was brought into the 
Maison royale de sante, having suffered from severe head- 
ache, vertigo, etc., for fifteen days, which finally became 
fixed at the occiput. During the first three days in the hos- 
pital, " he was in a continual state of agitation ; the move- 
ments of the members, on the right as well as the left 
side, were sometimes so 'brusques and disordered that they 
resembled convulsive movements." Soon the respiration 
became disturbed, and he died in asphyxia. " Upon post- 
mortem examination, there was found general injection 
of the meninges ; nothing particular in the cerebral hemi- 
spheres; a moderate quantity of serum in the ventricles; 
reddish softening of the left hemisphere of the cerebellum in 
its posterior and inferior half; no other lesion" (Andral, 
op. tit., p. 490). 

The only marked symptom relating to the movements in 
this case was a certain amount of irregularity and convulsive 
action of the muscles, while the patient was in bed. The 
case is not strong in its bearings, either for or against the 
coordination-theory ; for there must have been a great 
amount of irritation of the encephalic centres, and it would 
certainly be difficult to note disturbance of equilibration or 
of coordination in a patient confined to the bed. 

The third case is quoted by Andral from Lallemand, and 
is taken by Lallemand from Delamare. 



3T8 NERVOUS SYSTEM. 

CASE III. " M. Guerin, vicar at Gezeville, forty-six years 
of age, of a good temperament, strong, and corpulent, with 
a good appetite, complained of a dull pain, which finally be- 
came acute, under the frontal bone. For a year he experi- 
enced attacks of vertigo and vomiting, without fever. He 
staggered on his legs, and was often near falling forward. 
The treatment employed was antiphlogistic and derivative." 

On post-mortem examination, the cerebrum was found 
entirely healthy, but the envelop of the cerebellum was col- 
lapsed, folded, and only contained about the half of an egg- 
shell full of a brown and fetid, lymphatic*o-purulent liquid. 1 

This case, as far as the description goes, shows marked 
difficulty in equilibration or coordination. 

If the reader have carefully studied the foregoing analysis 
of Andral's cases, he will see that eighty-five may be thrown 
out altogether, leaving but eight ; and of these eight cases, 
five are so imperfectly described, and the disorganization of 
the cerebellum is so restricted, that they may also be disre- 
garded. The ninety-three cases are thus reduced to three. 
Of these three cases, in two, it is uncertain whether or not 
there were deficiency of coordinating power ; and in one, the 
difficulty in equilibration or coordination was distinctly noted. 
This, we conceive, disposes of the much-quoted ninety-three 
cases of Andral ; and they are certainly not opposed to the 
view that the cerebellum is the organ of equilibration or 
muscular coordination. 

In addition to the cases collected by Andral, there are 
numerous other instances on record of disease confined to 
the cerebellum. 

CASE IV. An interesting case of disease of the cere- 
bellum was reported by Gall, in 1823. 3 This patient " com- 
plained for several months of a very disagreeable sense of 
pressure at the nucha, and a tendency to fall forward as if 

1 LALLEMAND, Recherche* analomico-pathologiques sur rencephale, Paris, 1823, 
tome ii., p. 39. 

2 GALL, Sur Icsfonctions du cerveau, Paris, 1823, tome Hi., p. 341. 



FUNCTIONS OF THE CEREBELLUM. 379 

he saw a precipice at his feet. Several physicians attributed 
these symptoms to haemorrhoids ; for myself, I concluded 
that there was an organic disease in the brain. Several 
months after, the patient died, and we found on the ten to- 
riuni a fleshy mass two inches in diameter, which had com- 
pressed the cerebellum." 

CASE Y. In 1826, Fetiet reported a case of disease, in 
which the cerebellum was entirely destroyed, its tissue being 
broken down into a sort of whitish ~bouillie* The cerebrum 
was healthy. ' The observation was made in 1796. The pa- 
tient, before death, was observed to present a remarkable 
tendency to walk backward. He rose from his seat with 
difficulty, and, once erect, the first movements of the feet 
were lateral, and he finally walked by moving the feet from 
before backward. His locomotion consisted simply in pass- 
ing from his own to an adjoining bed in the ward, a distance 
of about six feet. 

CASE VI. One of the most remarkable cases, and the one 
most frequently quoted by physiological writers, was report- 
ed by Combette, in 1831. a This patient, Alexandrine La- 
brosse, in her seventh year, was seen by M. Miquel. Since 
the age of five years only had she been able to sustain her- 
self on her feet. M. Miquel was struck with her slight de- 
velopment and the feebleness of the extremities. At the 
age of nine and a half years, she was admitted into the Or- 
phelins. ""\Vhen spoken to, she answered with difficulty 
and hesitation. Her legs, although very feeble, enabled her 
still to walk, but she often fell." She was first seen by M. 
Combette, in January, 1831. She had then kept the bed for 
three months; was constantly lying on the back, nd could 
scarcely move the legs ; she used her hands with ease. She 
died of some intestinal disorder, March 25, 1831. On post- 

1 PETIET, Journal de physiologic, Paris, 1826, tome yi., p. 162, et seq. 

2 COMBETTE, Observation d"une jeune Jille, morte dans sa onzieme annee, chcz 
laquelk il y avail absence complete du cervelet, dcs pedoncules posterieures et de la 
protuberance annulaire. Journal de physiologic, Paris,. 1831, tome xi., p. 27, etseq. 



380 NERVOUS SYSTEM. 

mortem examination, " in place of the cerebellum there was 
a cellular membrane, gelatiniform, semicircular, from eigh- 
teen to twenty lines in its transverse diameter." There was 
no trace of the pons Yarolii. Combette states that Alex- 
andrine Labrosse was able to walk for several years, always, 
it is true, in an uncertain manner ; later, her legs became 
more and more feeble, and finally she ceased to be able to 
sustain her weight. She had the habit of masturbation. Com- 
bette further states that this observation is not in accord 
"with the experiments of Flourens, which tend to show 
that the cerebellum is the regulator of movements." The 
encephalon was also examined by Guillot, who noted ab- 
sence of the cerebellum and of the pons. 

This case is somewhat imperfect, as it was not seen by 
Combette until the patient had kept the bed for three 
months. By some writers, it is quoted in favor of, and by 
some, in opposition to the view that the cerebellum coordi- 
nates the muscular movements. It was not a case of simple 
disease of the cerebellum, as the pons and the posterior pe- 
duncles were also absent. It was noted, before the case was 
seen by Combette, that the patient walked in an uncertain 
manner and often fell. 

Several cases of injury of the cerebellum are reported by 
Larrey. 1 

CASE YII. One case is described, in which the patient 
was struck by a ball from a blunderbuss, which grazed the 
occipital protuberances. There was no disturbance of move- 
ment. The patient died on the thirty-ninth day, in opisthot- 
onos. On post-mortem examination, "the occipital bone 
had sustained a considerable loss of substance ; the slit into 
the dura mater, to which we have alluded, corresponded to 
the centre of the right lobe of the cerebellum, which was 
sunk downward and was of a yellowish color, but free from 
suppuration or effusion. The medulla oblongata and spinal 

1 LARREY, Injuries of the Cerebellum. Observations on Wounds, etc., Phila- 
delphia, 1832, p. 199, et seq. 



FUNCTIONS X>F THE CEEEBELLUM. 381 

marrow bore a dull,- white aspect, were of greater consist- 
ence than is natural, and had lost about a quarter of their 
size ; the nerves arising from them appeared to us also 
to be in a state of atrophy near their origin" (Larrey, 
op. cit., p. 207). 

CASE VIII. Another patient was struck by a piece of 
wood on* the right side of the head. He was found dead a 
little over three months after the injury. " The right hemi- 
sphere of the cerebellum was entirely disorganized by an 
abscess which pervaded its whole substance " (Larrey, op. 
cit., p. 210). No disturbances of movement were noted. 

CASE IX. Another patient had erysipelas following a 
fall on the side of the head, and abscess. He lived for three 
or four months. Five or six weeks after the injury, he had 
severe pains in the occiput, and, " when standing he could 
with difficulty only preserve his equilibrium." On post- 
mortem examination, the deep-seated vessels of the cere- 
brum were found injected. "We found, in the left lobe 
of the cerebellum, about three tablespoonfuls of pus of a 
whitish and gelatinous aspect, which had encroached upon, 
or rather displaced entirely, the hemisphere of the cerebel- 
lum ; this purulent substance was enveloped within the pia 
mater, which had acquired a somewhat firmer consistence, 
and, as in the subject of the preceding case, assumed a pearly 
color. The other half of the cerebellum was shrivelled, and 
the medullary substance forming the arbor vitse was of a 
grayish color and very dense " (Larrey, op. cit., p. 211). 

The first of these cases was found by Larrey to be asso- 
ciated with extinction of sexual appetite, and atrophy of the 
organs of generation. In the first two cases, judging from 
the results of experiments on animals, there was not enough 
injury of the cerebellum to necessarily influence the power 
of coordination. In the last case, there was difficulty in 
equilibration, but also some paralysis. 

A number of cases, which it is unnecessary to detail 
fulry, are cited by Wagner, in the Journal de la physiologic, 



382 NEKVOTJS SYSTEM. 

in which tottering gait and want of equilibration or of mus- 
cular coordination were noted, in connection with greater or 
less disorganization of the cerebellum. 1 In the same jour- 
nal, is a brief note of a case, reported by Laborde, in which 
there was a large cyst in the cerebellum, with incomplete 
paraplegia and " want of coordination of the movements of 
progression." 2 

CASE X. A most remarkable and carefully-observed case 
of atrophy of the cerebellum was reported by Dr. Fiedler, 
in 18G1. 3 The subject of this observation, a man, aged about 
fifty years, had remarkable peculiarities in his movements 
for thirty years. After the age of twenty years, it is stated 
that " he could no longer walk with as much certainty as 
before; the gait was staggering (taumelnd). . . . Not only 
in the house, but also in the street, the patient often fell, so 
that he was very frequently taken for a drunkard, and was 
either carried home or taken to the police-station. It is said 
that he never had drunk spirituous liquors. 

" Sometimes the patient walked backward, but only a few 
steps. He never had any turning movements ; the gait was 
always tottering (wacklig) and slow " (Fiedler, op. tit., p. 
251). He never fell forward, but always on the back. On 
post-mortem examination, the cerebrum was found healthy, 
" but the cerebellum was atrophied, especially at its posterior 
and inferior portion, and was reduced in size at least one- 
half" (Fiedler, op. cit., p. 258). This case presented the 
phenomena of defective coordination to a marked degree. 
Nothing is said of vertigo. 

CASE XI. In an elaborate article by Lussana, on the 
cerebellum, a case is quoted from Pourfour du Petit, in 
which a soldier, who received a gunshot-wound traversing 

1 WAGNER, Recherches critiques et experimentales sur les fonctions du ccrveau. 
Journal de la physiologic, Paris, 1861, torr.e iv., p. 386. 

8 Ibid., p. 637. 

8 FIEDLER, Ein Fall von Verkummerung des Cerebellum. Zcitschrift far ra* 
tionelle Medicin, Leipzig und Heidelberg, 1861, Bd. xi., S. 250, et seq. 



FUNCTIONS OF THE CEKEBELLUM. 383 

the left lobe of the cerebellum, immediately presented " a 
great disorder in his movements." 

Among the most striking of the cases of disease of the 
cerebellum, are two observed by Vulpian. 

CASE XII. The first was a woman, forty-nine years of 
age, in the hospital of la Salpetriere. " All of the move- 
ments were preserved, but locomotion was most irregular 
and difficult ; she could only walk in the most lizarre man- 
ner, resting on a chair which she placed before her at every 
step, and, in spite of her efforts at equilibration, she often 
fell." This patient, however, retained great muscular power. 
On post-mortem examination, " the cortical gray substance 
of the cerebellum was found entirely atrophied : all the 
nerve-cells of this layer had disappeared." There was con- 
siderable reduction in the size of the cerebellum. The cor- 
pora dentata were perfectly preserved, " showing that these 
parts, at all events, have but a slight office in coordination." 8 

CASE XIII. The second case presented an old softening, 
about the size of a hazel-nut, destroying a corresponding 
amount of the cerebellar substance of one of the hemispheres. 
The corpus dentatum was completely destroyed. This wom- 
an " walked well, but it appears nevertheless that she vacil- 
lated very slightly in her gait, without, however, a tendency 
to fall." 3 

"We have thus cited quite a number of cases of disease 
confined to the cerebellum, in which there was marked dis- 
turbance in the muscular movements ; but there are others, 
in which the movements were unaffected. As an example 
of the latter, we may refer to a case cited from Bouvier, by 
Prof. Hammond. 

CASE XIY. In this case, the movements of the limbs 
were all preserved. On post-mortem examination, there 
was found an abscess involving the two outer thirds of the 

1 LUSSAXA, Lemons sur les fonctions du cervellet. Journal de la physiologic, 
Paris, 1862, tome v., p. 429. 

3 VULPIAN, Systeme ncrveiix, Paris, 1866, p. 629. 3 Op. tit., p. 632. 

125 



384 NERVOUS SYSTEM. 

left hemisphere of the cerebellum ; the walls of this cavity, 
which contained several tablespoonfuls of pus, were soft- 
ened. 

" As M. Bouvier remarks, a circumstance of great inter- 
est connected with this case is the entire absence during life 
of any symptoms indicating an augmented sensibility, loss 
of equilibrium, or excitation of the genital organs." x 

With regard to this case, it is evident that the disease of 
the cerebellum was of slow development and did not involve 
enough of its substance to necessarily interfere with its func- 
tions, as has been clearly shown in other pathological cases 
and in experiments upon animals. 

Prof. Hammond also reports two interesting cases which 
came under his own observation. 2 

CASE XY. " In 1851, a Mexican shepherd was attacked 
near Cebolleta, in !N"ew Mexico, by Navajo Indians. He 
managed to escape, but in fleeing from his enemies received 
an arrow-wound in the posterior part of the head. He was 
on horseback, and, though stunned by the blow, maintained 
his seat in the saddle. So firmly was the arrow implanted 
that the shaft became detached by his efforts to remove it, 
leaving the head of the weapon in the skull. I saw him 
about two hours subsequently. He was then in full posses- 
sion of his senses and was suffering no pain. There were, 
however, constant vertigo and nausea, together with a sen- 
sation, as he described it, as if his head were balanced on a 
very delicate point, and the least inclination to one side 
or the other would cause it to fall off. On examining the 
wound, I found the arrow still sticking in the bone, and I 
had to use considerable force before I could remove it. It 
had entered to the extent of an inch and a half a little be- 
low and to the left of the occipital protuberance wounding 
the left lobe of the cerebellum. The vertigo continued all 

1 HAMMOND, The Physiology and Pathology of the Cerebellum. Quarterly 
Journal of Psychological Medicine, New York, 1869, vol. iii., p. 237. 
8 Loc. crit. 



FUNCTIONS OF THE CEREBELLUM. 385 

that night, but the nausea and vomiting stopped in the 
course of a few hours. 

" The next day he attempted to walk, but was obliged to 
desist on account of the vertigo. ' He felt,' he said, ( as if 
he were drunk,' and he staggered just like a drunken man. 
This feeling of vertigo continued for several weeks, lasting 
all through the period of suppuration. Gradually it disap- 
peared, though even after the lapse of a year he felt giddy 
on making any unusual exertion. At no time was there any 
difficulty in coordinating the muscles of the upper or lower 
extremities. The latter were simply affected through the ver- 
tigious sensation. The sensibility was unaffected through- 
out the whole progress of the case. 

CASE XVI. " The other case was that of a man who, for 
several months, had suffered with vertigo, occasional con- 
vulsions, attacks of nausea and vomiting, and a constant and 
violent pain affecting the back of the head. These symp- 
toms had come on subsequently to a severe blow which he 
had received on the back of the head, in consequence of 
raising himself too soon while the horse he was riding was 
passing under a low archway. 

" When this man attempted to walk he reeled and stag- 
gered as if he were drunk, but his movements were very 
different from those which we now recognize as character- 
izing locomotor ataxia. The upper extremities, and the or- 
gans of speech, were not affected ; he had the entire control 
of his legs when lying down, and there was no diminution 
of sensibility anywhere. At last he became paraplegic, and 
died in a convulsion. The post-mortem examination showed 
the existence of an abscess, which had obliterated nearly the 
whole of the left lobe of the cerebellum." 

The interpretation of these two cases depends, apparently, 
upon the ideas concerning the functions of the cerebellum, 
with which they are regarded. We should consider them 
as very strong evidence that the cerebellum regulates equi- 
libration and muscular coordination. Prof. Hammond re- 



386 NERVOUS SYSTEM. 

gards them as in accordance with his idea, that injury of 
the cerebellum does not affect coordination, but simply pro- 
duces vertigo. It remains for the reader to judge whether 
or not the phonomena observed indicate want of coordinating 
power. 

We now come to the main question, whether or not, in 
view of the results of experiments on animals and the phe- 
nomena observed in cases of disease or injury of the cere- 
bellum, this nerve-centre presides over coordination of ac- 
tion of the muscles, which is certainly necessary to equili- 
bration, except the muscles of the face and those concerned 
in speech. This question seems to us to be capable of a 
definite answer. 

Every carefully-observed case that we have been able to 
find, in which there was uncomplicated disease or injury of 
the cerebellum, provided the disease or injury involved more 
than half of the organ, presented great disorder in the gen- 
eral movements, particularly those of progression. AVe have 
collected the more or less complete reports of sixteen cases. 
In Case II., there was softening of one-half of one hemisphere, 
and remarkable convulsive movements. In Case VI., the 
one so often quoted from Combette, the gait was uncertain, 
with frequent falling ; there was incomplete paralysis ; but, 
in addition to the absence of the cerebellum, there was no 
pons Yarolii. In Case VII., there was no disturbance of 
movement, and there was partial degeneration of one lateral 
lobe. In Case VIII., there was no disturbance of move- 
ment, and disorganization of one lateral lobe of the cerebel- 
lum. In Case XIII., there was slight loss of substance in 
one lateral lobe of the cerebellum, and slight " vacillation " 
in the movements. In Case XIV., there was an abscess in- 
volving two-thirds of one lateral lobe, and the movements 
of the limbs were preserved. In Cases I., III., IV., V., IX., 
X., XI., XII., XV., XVI., ten out of sixteen, there was 
difficulty in muscular coordination, which was invariably in 



FUNCTIONS OF THE CEREBELLOI. 3S7 

direct ratio to the amount of cerebellar substance involved 
in the disease or injury. We do not make the reservation, 
that more than half of the cerebellum must be destroyed in 
order necessarily to produce difficulty in muscular coordina- 
tion, on purely theoretical grounds, but regard this point as 
positively demonstrated by experiments on animals. These 
experiments show that one-half of the organ is capable of 
performing the function of the whole. AVe have an analogy 
to this in the action of the kidneys, one of which is sufficient 
for the elimination of the effete constituents of the urine, 
after the other has been removed. 

Notwithstanding the contrary views of many physiologi- 
cal writers, we are firmly convinced, from experiments and 
a careful study of pathological facts, that there is no one 
point in the physiology of the nerve-centres more definitely 
settled than that the cerebellum presides over equilibration 
and the coordination of the muscular movements, particu- 
larly those of progression. In this statement, we make ex- 
ceptions in favor of the movements of respiration, degluti- 
tion, of the face, and of those concerned in speech, as well as 
the involuntary movements generally. As another example 
of a nerve-centre presiding over muscular coordination, we 
have the instance of the portion of the left anterior lobe of 
the cerebrum, which coordinates the action of the muscles 
concerned in speech. 

The theory that the disordered movements which follow 
injury of the cerebellum are due simply to vertigo is not 
tenable. In only three of the cases cited, is vertigo men- 
tioned; and in two, the word vertigo seems to be used 
rather as an explanation of the phenomena observed, than 
in their simple description. There is a disease involving the 
semicircular canals and other parts of the internal ear, 
called Meniere's disease, in which there is marked want of 
equilibration and muscular coordination, attended with, and 
probably dependent upon vertigo. The vertigo is always 
very distinct, and is mentioned in all of these cases ; and 



388 NERVOUS SYSTEM. 

though, it is less in the recumbent posture, it is never en- 
tirely absent. A very elaborate article on certain affections 
of the inner ear, including Meniere's disease, with numer- 
ous illustrative cases, was published by Dr. Knapp, in the 
Archives of Ophthalmology and Otology, New York, 18T1, 
vol. ii., No. i. A careful study of these cases, comparing 
them with the cases of deficient coordination from disease of 
the cerebellum, cannot fail to show a great difference be- 
tween the phenomena following cerebellar disease and the 
muscular phenomena due to well-marked and persistent 
vertigo. 1 

Connection of the Cerebellum with the Generative Func- 
tion. The fact that the cerebellum is the centre for equili- 
bration and the coordination of certain muscular movements 
does not necessarily imply that it has no other functions. 
The idea of Gall, that " the cerebellum is the organ of the 
instinct of generation," 2 is sufficiently familiar ; and there 
are numerous facts in pathology that show a certain relation 
between this nerve-centre and the organs of generation, 
though the idea that it presides over the generative function 
is not sustained by the results of experiments on animals, 
or by facts in comparative anatomy. 

In experiments on animals in which the cerebellum has 
been removed, there is nothing pointing directly to this part 
as the organ of the generative instinct. Flourens removed a 
great part of the cerebellum in a cock. The animal survived 
for eight months. It was put several times with hens, and 
always attempted to mount them, but without success, from 
want of equilibrium. In this animal, the testicles were 
enormous. 3 This observation has been repeatedly confirmed, 
and there are no instances in which the cerebellum has been 

1 KNAPP, A Clinical Analysis of the Inflanvnatory Affections of the Inner Ear, 
New York, 1871. 

2 GALL, Sur les fonctions du cerveau, Paris, 1825, tome Hi., p. 245. 

3 FLOURENS, Systeme nerveux, Paris, 1842, p. 163 



FUNCTIONS OF THE CEREBELLUM. 389 

removed with apparent destruction of sexual instinct. In a 
comparison of the relative weights of the cerebellum in stal- 
lions, mares, and geldings, Leuret found that, far from being 
atrophied, the cerebellum of geldings was even larger than 
in either stallions or mares. 1 

In the numerous cases of disease or injury of the cere- 
bellum, to which we have already referred, there are some, 
in which irritation of this part has been followed by persistent 
erection and manifest exaggeration of the sexual appetite, 
and others, in which its extensive degeneration or destruction 
has apparently produced atrophy of the generative organs 
and total loss of sexual desire. There are also certain cases 
of this kind which we have not yet cited. Serres gives the 
history of several cases, in which irritation of the cerebellum 
was followed by satyriasis or nymphomania, but in other 
cases, there were no symptoms referable to the generative 
organs. 3 In the case reported by Combette, the patient had 
the habit of masturbation. 3 Dr. Fisher, of Boston, gives an 
account of two cases of diseased or atrophied cerebellum, with 
absence of sexual desire, and one case of irritation, with 
satyriasis. 4 Similar instances are given by other writers, 
which it is unnecessary to detail. We have already cited 
the observations of Budge and of Hammond, in which me- 
chanical irritation of the cerebellum was followed by move- 
ments of the uterus, testicles, etc. 6 For other citations bear- 
ing upon the connection between the cerebellum and the 
generative function, the reader is referred to the elaborate 
memoir by Prof. Hammond. 6 

1 LEURET, Ana'omie comparee da sysleme nerveux, Paris, 1839-1857, tome i., 
p. 429. 

2 SERRES, Sur les maladies organiques du cervelet. Journal de physiologic, 
Paris, 1822, tome ii., p. 172, et seq., and p. 249, et seq. 

3 Journal de physiologic, Paris, 1831, tome xi., p. 30. 

4 FISHER, Contributions Illustrative of the Functions of the Cerebellum. Amer- 
ican. Journal of tjie Medical Sciences, Philadelphia, 1838, No. xlv., p. 352, et seq. 

5 See page 363. 

6 Quarterly Journal of Psychological Medicine, New York, 1869, vol. Hi., p. 
219, et seq. 



390 NERVOUS SYSTEM. 

Although there are many facts in pathology which are 
opposed to the view that the cerebellum presides over the 
generative function, there are numerous cases which go to 
show a certain connection between this portion of the central 
nervous system and the organs of generation in the human 
subject. But this is all that we can say upon this im- 
portant point ; certain it is that the facts are not sufficiently 
numerous, definite, and invariable, to sustain the doctrine 
that the cerebellum is the seat of the sexual instinct. 

Development of the Cerebellum in the Lower Animals. 
The study of the comparative anatomy of the cerebellum has 
little physiological interest, except in so far as it bears upon 
our knowledge of its physiology. From this point of view, 
there is little to be said concerning its development in the 
animal scale. We can hardly establish a definite relation 
between this particular part of the encephalon and the corn- 
plicated character of the muscular movements ; for, as we 
pass from the lower to the higher orders of animals, we have 
other parts of the brain, as well as the cerebellum, devel- 
oped in proportion to the increased complexity of the mus- 
cular system. !Nor can we connect the comparative anatomy 
of the cerebellum with the ideas of the functions of this organ 
in connection with generation. The amphioxus lanciolatus 
has no cerebellum, and this organ, therefore, is not indis- 
pensable to generation. In some animals remarkable for 
salacity, the cerebellum is not unusually large ; and facts of 
this kind might be multiplied ad infinitum. 

Paralysis from Disease or Injury of the Cerebellum. It 
is not unusual to observe disorganization of a considerable 
amount of cerebellar substance without paralysis ; and, 
indeed, we are inclined, upon this point, to adopt the view 
advanced by Yulpian, that, of itself, disease of the cerebellum 
is not attended with hemiplegia, this condition obtaining 
only when the peduncles, the pons ; or the motor tracts of 



PARALYSIS FROM DISEASE OF THE CEREBELLUM. 391 

the cord are directly or indirectly involved. 1 As far as the 
physiology of the cerebellum bears upon this point, there is 
no reason why simple disease of its substance should produce 
hemiplegia. As in cerebral affections disease of the hemi- 
spheres is followed by hemiplegia, as the rule, only when the 
corpora striata, the optic thalami, or the pons, is involved, 
either by compression or disorganization, so in disease of the 
cerebellum, there must be some disturbance of the motor 
tracts. 

It is a curious fact, also, that in certain cases of disease 
of the cerebellum, without any affection of the cerebrum, in 
which hemiplegia exists, the paralysis occurs on the opposite 
side of the body, while in others, it is on the same side as the 
cerebellar lesion. According to Yulpian, the hemiplegia is 
direct or crossed, the situation of the paralysis depending 
upon the parts of the motor tracts that are compressed. In 
simple softening of the substance of the cerebellum, as we 
have just remarked, there is, of necessity, no paralysis, but 
haemorrhage or tumors may impinge upon one or another 
of the motor tracts of the encephalon or the cord. 8 

In certain of the cases collected by Andral, there was a 
lesion of one lateral lobe of the cerebellum, associated with a 
lesion of the cerebral hemisphere of the opposite side. In 
these cases, the paralysis did not affect both sides of the body, 
but was always situated on the side opposite to the lesion of 
the cerebrum, the same side as the cerebellar disease. 8 

AVe have thus only discussed those views with regard to 
the functions of the cerebellum which are supported by ex- 
perimental or pathological facts, and have not touched upon 
the vague and unsupported ideas advanced by various writers 
before the publication of the remarkable observations of 
Flourens. There is 110 proof that the cerebellum is the organ 

1 YCLPIAN, Systeme nerveux, Paris, 1866, p. 608. 

2 TULPIAX, loc. cit. 

3 ANDRAL, Clinique mtdicale, Bruxelles, 1834, tome v., p. 481. 



392 NERVOUS SYSTEM. 

presiding over memory, the involuntary movements, general 
sensibility, or the general voluntary movements. The only 
view that has any positive experimental or pathological 
basis is that it presides over equilibration and the coordina- 
tion of certain muscular movements, and is in some way 
connected with the generative function. 



CHAPTEE XIY. 

GANGLIA AT THE BASE OF THE ENCEPHALON. 

Corpora striata Optic thalami Tubercula quadrigemina, or optic lobes Gan- 
glion of the tuber annulare Medulla oblongata Physiological anatomy of 
the medulla oblongata Functions of the medulla oblongata Connection 
of the medulla oblongata with respiration Vital point Connection of the 
medulla oblongata with various reflex acts Rolling and turning movements 
following injury of certain parts of the encephalon General properties of 
the peduncles. 

AT the base of the encephalon, are found several collec- 
tions of gray matter, or ganglia, some of which have func- 
tions distinct from those already described in connection 
with the cerebrum and the cerebellum ; but most of them 
are so difficult of access in living animals, that we possess 
very little definite information, even with regard to their 
general properties. We have, however, a tolerably complete 
knowledge of the functions of the medulla oblongata and 
the tubercula quadrigemina, and have some idea of the physi- 
ology of the tuber annulare ; but the functions of the corpora 
striata, optic thalami, ventricles, pineal gland, peduncles, 
etc., are not at all understood, and the speculations of the 
older writers, with the indefinite experiments of modern 
physiologists, upon these parts, will be passed over very 
briefly. 

Corpora Striata. 

These bodies are somewhat pear-shaped, and are situated 
at the base of the brain, partly without the cerebral hemi- 
spheres and partly embedded in their white substance. 



394 NEKVUPS SYSTEM. 

Their rounded base is directed forward, and the narrower 
end, backward and outward. Their external surface is gray, 
and they present, on section, alternate striae of white and 
gray matter, w r hich appearance has given them the name of 
corpora striata. Between the narrow extremities of these 
bodies, are situated the optic thalami. 

There is very little to be said with regard to the func- 
tions of the corpora striata. Longet has found them com- 
pletely inexcitable and insensible to mechanical irritation. 1 
The idea of M agendie, that a tendency to backward move- 
ments resided in these bodies, while the cerebellum exerted 
an antagonistic action, is not sustained by experiments. 8 
When they are removed, disturbing the hemispheres as little 
as possible, there appears to be no paralysis, either of motion 
or sensation. 3 

"We have obtained a little more information regarding 
the functions of the corpora striata, from cases of cerebral 
haemorrhage in the human subject, than from experimental 
investigations. In apoplexy, when the corpus striatum on 
one side is alone involved, there is paralysis of motion of the 
opposite lateral half of the body, the general sensibility usual- 
ly being unaffected. Facts of this kind show that the action 
of the corpora striata is crossed ; and they further illustrate 
their connection with the motor tract from the hemispheres. 

There is no reason to suppose that the corpora striata are 
the centres of olfaction, as was at one time thought, for they 
are sometimes absent in animals possessing very large olfac- 
tory nerves, and are very largely developed in the cetacea, 
in which the olfactory apparatus is rudimentary. 4 

Optic Thalami. 

From their name, we should infer that the optic thalami 
have some important function in connection with vision ; 

1 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 419. 

2 MAGENDIE, Precis elementaire de physiologic, Paris, 1836, tome i., p. 404. 
8 LONGET, loc. cit. 4 LONGET, loc. cit. 



OPTIC THALAm. 395 

but they serve merely as beds for the optic commissures, and 
give to the nerves but very few fibres. They are oblong 
bodies, situated between the posterior extremities of the 
corpora striata, and resting upon the crura cerebri on the 
two sides. They are white externally, and, in their interior, 
present a mixfure of white and gray matter. Longet has 
destroyed them upon the two sides, carefully avoiding injury 
of the optic tracts, and noted* no interference with vision or 
the movements of the iris. 

The optic thalarni seem, from experiments upon animals, 
to have a peculiar crossed action upon the muscular system. 
While their mechanical irritation produces neither pain nor 
convulsive movements, showing that they arc insensible and 
in excitable, the extirpation of one optic thalamus produces 
enfeeblemeiit of the muscles of the opposite lateral half of 
the body, without actual paralysis. 1 "When both have been 
removed, there is general debility of the muscular system. 
It is unnecessary to refer to other experiments upon these 
parts, which have been very indefinite in their results, or to 
allude to the "circular" movements produced by lesion 
upon one side, involving also the crus cerebri ; for, beyond 
the statement just made, the function of the optic thalami 
is unknown. 

"We derive but little information concerning the optic 
thalami from cases of cerebral haemorrhage in the human 
subject ; for it is not common to have disease involving 
these parts and not affecting other centres. In some cases 
of lesion limited to the optic thalamus on one side, there is 
paralysis of sensation of the opposite lateral half of the body, 
without actual paralysis of motion, though the movements 
are generally feeble. "When the brain-lesion involves both 
the corpus striatum and the optic thalamus on one side, 
which is more common, there is paralysis of motion, with 
loss or disorder of sensibility, on the opposite side of the 
body. These facts illustrate, to a certain extent, the ana- 

1 LGXGET, Traite de jthysioloffie, Paris, 1869, tome iii., pp. 412, 413. 



NERVOUS SYSTEM. 

tomical connection of the optic thalami with the sensory 
tracts, though, in experiments on animals, destruction of 
these parts does not necessarily affect the general sensibility. 

Tubereula Quadrigemina. 

These little bodies, sometimes called the optic lobes, are 
rounded eminences, two upon, either side, situated just be- 
hind the third ventricle. The anterior, called the nates, 
are the larger. These are oblong and of a grayish color ex- 
ternally. The posterior, called the testes, are situated just 
behind the anterior. They are rounded, and rather lighter 
in color than the anterior. Both contain gray nervous mat- 
ter in their interior. They are the main points of origin 
of the optic nerves, and are connected by commissural fibres 
with the optic thalami. In birds, the tubercles are two in 
number, instead of four, and are called the tubercula bi- 
gemina. 

It is probable that the tubercula quadrigemina are in ex- 
citable and insensible. "When pain and convulsive move- 
ments have apparently followed their mechanical irritation 
in living animals, these phenomena have probably been due 
to excitation or stimulation of the motor or sensory commis- 
sural fibres which pass beneath them. At least, this seems 
to be the proper conclusion to draw from the experiments 
of Longet. 1 

As regards the function of the optic lobes, aside from 
their action as reflex nervous centres for the movements of 
the iris, there is little to be said, except that they preside over 
the sense of sight. They are easily reached and operated 
upon in birds, where they are very large, and, as Flourens 
demonstrated many years ago, their extirpation is followed 
by total loss of sight, as well as abolition of the reflex move- 
ments of the iris. 8 In birds and in those mammals in which 

1 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 407. 
8 FLOURENS, Sysieme nerveux, Paris, 1842, p. 145. 



TUBERCULA QUADEIGEMIXA. 397 

they Lave been operated upon, the action in vision is crossed ; 
i. e., when the lobe is removed upon one side, the sight is 
lost in the opposite eye, vision in the eye upon the same 
side being unimpaired. We have long been in the habit, in 
class-demonstrations, of removing the optic lobe on one side 
from a pigeon, with the result just mentioned. The opera- 
tion is quite simple : A part of the skull is removed by the 
side of one hemisphere, and the optic lobe is seen, 'in the 
form of a large, white tubercle, between the posterior por- 
tion of the cerebrum and the cerebellum. A little slit is 
then made in its capsule, and the interior is broken up care- 
fully with a delicate forceps. The animal generally recovers 
from the operation, blinded in the eye upon the opposite 
side. In removing the portion of the skull, it is well not to 
go too for back, when there is danger of wounding the great 
venous sinus and complicating the operation by haemorrhage. 

In treating of the special sense of sight, in the next and last 
volume, we shall see that the decussation of the optic nerves 
is more complex in man than in birds, in which the nerve 
from one optic lobe passes totally and exclusively to the eye 
upon the opposite side. In man, most of the fibres of the 
optic nerve from one side pass to the eye upon the opposite 
side ; but a few fibres pass to the eye upon the same side, a 
few connect the tubercles upon the two sides, and a few con- 
nect the two eyes. It is not known whether or not, in man, 
the action of the tubercles in vision is exclusively crossed, as 
it appears to be in most of the inferior animals. 

The optic lobes undoubtedly serve as the sole centres 
presiding over the sense of sight, and not merely as avenues 
of communication of this sense to the cerebral hemispheres. 
A positive proof of this proposition lies in the fact that the 
sense of sight is preserved after complete removal of the 
cerebrum, provided that injury of the tubercles have been 
carefully avoided. 

AVe shall say nothing, in this connection, with regard to 
the movements of the iris, except that the reflex action by 



398 NEKVOUS SYSTEM. 

which the size of the pupil is modified is effected through 
the optic lobes as nerve-centres. The mechanism of the 
movements of the iris and their regulation through nervous 
action are questions of great interest, and are somewhat com- 
plex. We have already treated of them to some extent, in 
connection with the physiology of the third pair of nerves, 
and they will be considered still more fully in the section 
on the special sense of sight. 

Ganglion of the Tuber Annulare. 

The tuber annulare, called the pons Yarolii, or the 
mesocephalon, is situated at the base of the brain, just above 
the medulla oblongata. It is white externally, and contains 
in its interior a large admixture of gray matter. It presents 
both transverse and longitudinal white fibres. Its transverse 
fibres connect the two halves of the cerebellum. Its longi- 
tudinal fibres are connected below, with the anterior pyrami- 
dal bodies and the olivary bodies of the medulla oblongata, 
the lateral columns of the cord, and a certain portion of the 
posterior columns. Above, the fibres are connected with 
the crura cerebri, and pass to the brain. The superficial 
transverse fibres are wanting in animals in which the cere- 
bellum has no lateral lobes. 

The general properties of the tuber annulare have been 
Demonstrated in the most satisfactory manner by Longet. 
In his experiments, direct excitation of the superficial trans- 
verse fibres did not produce well-marked convulsive move- 
ments, and there were no convulsions when the posterior 
fibres were stimulated. When galvanization was applied to 
the deeper anterior fibres, convulsive movements were dis- 
tinct at each excitation. Stimulation of the posterior portion 
always produced pain. This was not constantly observed to 
follow irritation of the anterior portion, and, when pain oc- 
curred, it was thought to be due to irritation of the root of 
the fifth nerve. 1 

1 LONGET, Traiti de physiologic, Paris, 1869, tome iii., p. 394. 



GANGLION OF <THE TUBEE ANNCLAEE. 399 

The above experiments, it is true, are not as free iroin 
uncertainty as those made upon the more accessible parts of 
the eneephalon, but, as far as they go, they tend to show 
that the tuber annulare is both insensible and inexcitable in 
its superficial anterior portion, which is composed chiefly of 
commissural fibres from the cerebellum ; that it is excitable 
and probably insensible in its deeper anterior portion, which 
seems to be composed chiefly of descending motor conduct- 
ors ; and finally, that it is sensible and probably inexcitable 
in its posterior portion. 

The tuber annulare undoubtedly acts as a conductor of 
sensory impressions and motor stimulus to and from the 
cerebrum, as we would naturally expect from the direction 
of its fibres, and as has been repeatedly shown by cases of 
disease, particularly as regards motion. In addition, how- 
ever, judging from the fact that it contains numerous nod- 
ules of gray matter between fasciculi of white fibres, and 
that this gray matter contains cellular elements similar to 
those found in other nerve-centres, and from which new 
nerve-fibres undoubtedly originate, it would be inferred 
that these nodules have a distinct function, and give to the 
tuber annulare the properties of a nerve-centre. It will be 
interesting, therefore, to follow out the experiments upon 
this part, by which its action as a centre has been illustrated. 
These experiments are of two kinds : First, the removal of 
other encephalic ganglia, leaving only the tuber annulare, 
the medulla oblongata, and the cerebellum, and noting the 
properties or faculties retained by animals under these con- 
ditions. Experiments of this kind are tolerably definite, as 
we already know the general functions of most of the other 
encephalic ganglia. Second, to note the effects of extirpa- 
tioTi of the tuber annulare alone. 

If the cerebral hemispheres, the olfactory ganglia, the 
optic lobes, the corpora striata, and the optic thalami, be 
removed, the animal loses the special senses of smell and 
sight and the intellectual faculties, there is a certain amount 

128 



4:00 NERVOUS SYSTEM. 

of enfeeblement of the muscular system, but voluntary mo- 
tion and general sensibility are retained. There can be no 
doubt upon these points. As far as voluntary motion is 
concerned, an animal operated upon in this way is in nearly 
the same condition as one simply deprived of the cerebral 
hemispheres. There are no voluntary movements which 
show any degree of intelligence, but the animal can stand, 
and various consecutive movements are executed, which are 
entirely different from the simple reflex acts depending 
exclusively upon the spinal cord. The coordination of move- 
ments is perfect, unless the cerebellum be removed. As re- 
gards general sensibility, an animal deprived of all the en- 
cephalic ganglia except the tuber annulare and the medulla 
oblongata undoubtedly feels pain. This has been demon- 
strated in the most conclusive manner by Longet, 1 and has 
been shown even more satisfactorily by Yulpian. 8 In rabbits, 
rats, etc., after removal of the cerebrum, corpora striata, and 
optic thalami, pinching of the ear or foot is immediately 
followed by prolonged and plaintive cries. Both of the 
experimenters referred to insist upon the character of these 
cries as indicating the actual perception of painful impres- 
sions, and as very different from cries that are purely reflex, 
according to the ordinary acceptation of this term. Longet 
alludes to the voluntary movements and the cries observed 
in persons subjected to painful surgical operations, when 
incompletely under the influence of an anaesthetic, concern- 
ing the character of which there can be no doubt. He re- 
gards the movements as voluntary, and the cries as evidence 
of the acute perception of pain ; but it is well known that 
such patients have no recollection of any painful impression, 
though they have apparently experienced great suffering. 
As far as we can judge from what we positively know of the 
function^ of the encephalic centres, the pain under these 
circumstances is perceived by some nerve-centre, probably 

1 LONGET, Trai/e de physiologic, Paris, 1869, tome iii., p. 396. 

2 VULPIAN, Systeme nerveux, Paris, 1866, p. 542, et seq. 



GANGLION OF THE TUBER ANNULARE. 401 

the tuber annulare, but the impression is not conveyed to 
the cerebrum, and is not recorded by the memory. 

Taking all the experimental facts into consideration, the 
following seems to be the most reasonable view with regard 
to the function of the tuber annulare as a nerve-centre. 

It is an organ capable of originating a stimulus giving 
rise to voluntary movements, when the cerebrum, corpora 
striata, and the optic thalami, have been removed, and prob- 
ably regulates the automatic voluntary movements of station 
and progression. Many voluntary movements, the result of 
intellectual effort, are made in obedience to a stimulus trans- 
mitted from the cerebrum, through conducting fibres in the 
tuber annulare, to the motor conductors of the cord and the 
general motor nerves. 

The tuber annulare is also capable of perceiving painful 
impressions, which, when all of the encephalic ganglia are 
preserved, are also conducted to and are perceived by the 
cerebrum, and are remembered ; but there are distinct evi- 
dences of the perception of pain, even when the cerebrum 
has been removed. 

Cases of disease or injury of the tuber annulare on one 
side in the human subject show that its action is crossed. 
It is a curious fact that lesions of the encephalon involving 
the pons may be located during life by the existence of what 
is known as alternate paralysis ; i. e., there is hemiplegia on 
the side opposite to the brain-lesion, attended with paralysis 
of the facial on the same side as the lesion, so that the fa- 
cial palsy and the hemiplegia are on opposite sides of the 
body. We have already cited, in connection with the physi- 
ology of the facial nerve, the cases collected by Gubler, of 
this alternate paralysis, in illustration of the decussation of 
the deep fibres of origin of the facial ; for when the lesion 
involves parts of the encephalon anterior to or above the 
pons, the facial paralysis is on the same side as the hemi- 
plegia. 1 Additional cases of alternate paralysis have been 

1 See page 147. 



4:02 NERVOUS SYSTEM. 

reported by Brown-Sequard, in' an elaborate memoir on the 
physiology and pathology of the protuberance. 1 

Medulla Oblongata. 

The chief points of interest in the physiological anatomy 
of the medulla oblongata relate to the direction of its fibres, 
their connection with the gray matter embedded in its sub- 
stance, and the course of the filaments of origin of certain of 
the cranial nerves. Concerning the deep origin of the large 
root of the fifth, the motor-oculi externus, facial, pneumogas- 
tric, spinal accessory, and the sublingual, we shall have noth- 
ing to say in this connection, as we have already treated of the 
physiological anatomy of these nerves with sufficient minute- 
ness ; and we have now to study the functions of the medulla 
oblongata, and particularly its action as a nerve-centre. 

Physiological Anatomy of the Medulla Oblongata. The 
medulla oblongata is the oblong, enlargement which connects 
the spinal cord with the various encephalic ganglia. It is 
about an inch and a quarter in length, and nearly an inch 
broad, at its widest portion. It rests in the basilar groove 
of the occipital bone, extending from the atlas to the lower 
border of the tuber annulare, with its broad extremity 
above. Like the cord, it has an anterior and a posterior 
median fissure. 

Apparently continuous with the anterior columns of the 
cord, are the two anterior pyramids, one on either side. 
Yiewed superficially, the innermost fibres of these pyramids 
are seen to decussate in the median line ; but if these 
fibres be traced from the cord, it is found that they come 
from the white substance of its lateral columns, and that none 
of them are derived from the anterior columns. The fibres 
of the external portion of the anterior pyramids come from 

1 BROWN-SEQUARD, Recherclies sur la physiologic et la pathologic de la protu- 
berance annulaire. Journal de la physiologic, Paris, 1858, tome i., p. 755, etseq. ; 
and, Ibid., 1859, tome ii., p. 130, et seq. 



MEDULLA OBLONGATA. 403 

tlic anterior columns of the cord. At the site of the decus- 
sation, the pyramids are composed entirely of white mat- 
ter ; but as the fibres spread out to pass to the encephalon 
above, they present nodules of gray matter between the 
fasciculi. 

External to the anterior pyramids, are the corpora oliva- 
ria. These are oval, and are surrounded by a distinct 
groove. They are white externally, and contain a gray 
nucleus, called the corpus dentatum. 

External to the corpora olivaria, are the restiform bodies, 
formed exclusively of white matter, and constituting the pos- 
tero-lateral portion of the medulla. They are continuous 
with the posterior columns of the cord. The restiform bod- 
ies spread out as they ascend, and pass to the cerebellum, 
forming a great portion of the inferior peduncles. 

Beneath the olivary bodies, and between the anterior 
pyramids and the restiform bodies, are the lateral tracts of 
the medulla, called by the French, the intermediary fasciculi. 
These are composed of an intimate mixture of white and 
gray matter, and have a yellowish-gray color. They receive 
all that portion of the antero-lateral columns of the cord 
which does not enter into the composition of the anterior 
pyramids. These are frequently considered as parts' of. the 
restiform bodies, but they are peculiarly interesting, from the 
fact that they contain the gray centre presiding over respira- 
tion, and for that reason we have described them as distinct 
fasciculi. 

The posterior pyramids (fasciculi graciles) are the small- 
est of all. They pass upward to the cerebrum, without decus- 
sating, and are composed exclusively of white matter. As 
they pass upward, they diverge, leaving a space at the fourth 
ventricle. 

The fourth ventricle is in the medulla, and is bounded 
above, by the valve of Yieussens and the under surface of the 
cerebellum. In the lower part of the floor of the fourth ven- 
tricle, are several transverse fasciculi of white matter; but the 



4:04 NERVOUS SYSTEM. 

greatest part of this portion is composed of a layer of gray 
substance. 

The two lateral halves of the posterior portion of the me- 
dulla are connected together by fibres arising from the gray 
matter of the lateral tracts, or intermediary fasciculi, passing 
obliquely, in a curved direction from behind forward, to the 
raphe in the median line. There are also fibres passing from 
before backward, to form a posterior commissure, and fibres 
arising from the cells of the olivary bodies, which connect 
the gray substance of the lateral halves. Commissural fibres 
also connect the gray matter of the lateral tracts with the 
corpora dentata of the olivary bodies, and the olivary bodies 
with the cerebellum, their fibres forming part of the inferior 
peduncle of the cerebellum. In addition, it is probable that 
.fibres, taking their origin from all of the gray nodules of 
the medulla, pass to the parts of the encephalon situated 
above. 

As far as the fibres of origin of the nerves are concerned, 
it may be stated in general terms that a number of the motor 
roots arise from the gray matter of the floor of the fourth 
ventricle, the roots of the sensory nerves arising from gray 
matter in the posterior portions. 

Aside from purely anatomical demonstrations, the con- 
nection of the anterior pyramids of the medulla with the cor- 
pora striata has been shown by pathological observations. 
It is well known that, when the connection between the 
nerve-centres and the fibres is destroyed, these fibres after a 
time become degenerated. In old lesions of the corpora 
striata, Cruveilhier, Tiirk, and, more lately, Yulpian, have 
shown that, when the white substance is injured upon one 
side, there follow degeneration and atrophy of the fibres of 
the corresponding cerebral peduncle and anterior pyramid 
of the medulla, and of the lateral portion of the spinal cord 
upon the opposite side. 1 This important fact illustrates the 
connection between the lateral columns of the cord and the 

1 VULPIAN, Systeme nervevix, Paris, 1866, p. 470. 



MEDULLA OBLONGATA. 405 

anterior pyramids of the medulla oblongata, the decussation 
of the anterior pyramids, and the passage of fibres from the 
anterior pyramids to the corpora striata, in the substance of 
the cerebral peduncles. 

Functions of the Medulla Oblongata. 

It is. hardly necessary to discuss the functions of the me- 
dulla oblongata as a conductor of sensory impressions and of 
motor stimulus to and from the brain. We know that there 
is conduction of this kind from the spinal cord to the ganglia 
of the encephalon, and this must take place through the me- 
dulla ; a fact which is inevitable, from its anatomical relations, 
and which is demonstrated by its section in living animals. 
Xor is it necessary to dwell upon its general properties, in 
which it resembles the spinal cord, at least as far as has been 
demonstrated by experiments upon living animals or upon 
animals just killed. It is difficult to expose this part in the 
higher classes of animals, but the experiments of Longet * 
and of Yulpian 2 show that it is sensitive on its posterior sur- 
face and insensible in front. The difficulty of observing the 
phenomena which follow its irritation in living animals has 
rendered it impossible to determine the limits of its excita- 
bility and sensibility as exactly as has been done for the dif- 
ferent portions of the cord. 

It is also somewhat difficult to determine whether the ac- 
tion of the medulla itself, in its relations to motion and sen- 
sation, be crossed or direct. As regards conduction from the 
brain, the direction is sufficiently well shown by cases of ce- 
rebral disease, in which the paralysis, in simple lesions, is 
always on the opposite side of the body. Philipeaux and 
Yulpian have shown that, in the medulla, this crossed action 
is not distinct. After section of one lateral half of the me- 
dulla in dogs and Guinea-pigs, there was not complete pa- 

1 LOXGET, Traite de physiologic, Paris, 1869, tome ill, p. 377. 

2 YrLriAX, System* nerveux, Paris, 1866, p. 484. 



4:06 NEJRVOUS SYSTEM. 

ralysis of motion, either on one side or the other, though the 
animals operated upon were not able to stand. 1 

The action of the medulla as a reflex nerve-centre depends 
upon its gray matter. "When this gray substance is de- 
stroyed, certain of the important reflex functions are in- 
stantly abolished. From its connections with various of the 
cranial nerves, we should expect it to play an important part 
in the movements of the face, in deglutition, in the action of 
the heart and of various glands, etc., important points which 
will be fully considered in their appropriate place. Its 
most striking function, however, is in connection with respi- 
ration. 

Connection of the Medulla Oblongata with Respiration. 
It did not escape the observation of Galen, that when a 
section was made at the summit of the spinal cord, the ani- 
mal was suddenly destroyed. 2 This fact has been considered 
as well established, since the time of Galen, but in 1809, Le- 
gallois made a number of experiments upon rabbits, cats, 
etc., in which he showed that respiration depends exclu- 
sively upon the medulla oblongata and not upon the brain, 
and he further located the part which presides over this 
function at the site of origin of the pncumogastric nerves : 3 
" For, if we open the cranium of a young rabbit, and ex- 
tract the brain, by successive portions, from before back- 
ward, cutting it by slices, we can remove in this way all of 
the brain proper, and then the entire cerebellum and a part 
of the medulla oblongata. But it (respiration) ceases sud- 
denly when we include in a section the origin of the eighth 
pair of nerves (pneumogastrics)." The experiments of Le- 
gallois were repeated and confirmed before a commission 
from the French Institute, composed of Yon Humboldt, 

1 VULPIAN, Systeme ncrveux, Paris, 1866, p. 495 

2 GALENUS, De Anatomicis Admtnistrationibus, Liber viii., Cap. ix. Opera, 
Lipsiae, 1821, tomus ii., pp. 696, 697. 

3 LEGALLOIS, Experiences sur h prindpe de la vie. (Euvres, Paris, 1824, tome 
i., p. 64. The date of these experiments is given by Legullois on page 74. 



MEDULLA OBLONG ATA. 407 

Halle, and Percy. 1 Flourens, in his elaborate experiments 
upon the nerve-centres, extended the observations of Legal- 
lois, and limited the respiratory centre in the rabbit, between 
the upper border of the roots of the pneumogastrics and a 
plane situated about a quarter of an inch below the lowest 
point of origin of these nerves ; these limits, of course, vary- 
ing with the size of the animal. 3 Following these experi- 
ments, Longet has shown that the respiratory nervous centre 
does not occupy the whole of the medulla included between 
the two planes indicated by Flourens, but that it is confined 
to the gray matter of the lateral tracts, or the intermediary 
fasciculi. This was demonstrated by the fact that respiration 
persists in animals after division of the anterior pyramids 
and the restiform bodies. Subsequently, Flourens still far- 
ther restricted the limits of the respiratory centre, and fully 
confirmed the observations of Longet. 3 

The portion of the medulla oblongata above indicated 
presides over the movements of respiration, and is the true 
respiratory nerve-centre. Kearly all who have repeated the 
experiments of Flourens have found that the spinal cord 
may be divided below the medulla oblongata, and that all 
of the encephalic ganglia above may be removed, respiratory 
movements still persisting. It is a very common thing in 
vivisections to kill an animal by breaking up the medulla. 
In a dog, for example, we grasp the head firmly with the 
left hand, flex it forcibly on the neck, and penetrate with a 
stylet a little behind the occipital protuberance, entering be- 
tween the atlas and the skull. By a rapid lateral motion of 
the instrument, the medulla is broken up, and the animal in- 
stantly ceases to breathe. There are no struggles, no mani- 
festations of the distress of asphyxia ; the respiratory mus- 

1 LEGALLOIS, op. cit., tome i., p. 248. 

2 FLOUREXS, Systeme nerveux, Paris, 1842, p. 204. 

Flourens was in error when he stated (page 197) that Lorry was the first to 
show that animals were instantly killed by destruction of the summit of the 
ppinal cord, for this was distinctly indicated by Galen, in the second century. 

3 LONGET, Traite de physiologic, Paris, 1869, tome iii., pp. 387, 388. 



408 NEKVOUS SYSTEM. 

cles simply cease their action, and the animal loses instantly 
the sense of want of air. A striking contrast to this is pre- 
sented when the trachea is tied or when all of the respiratory 
muscles are paralyzed without touching the medulla. The 
same phenomena follow injury to the medulla in the human 
subject ; and in anaesthesia from the administration of chlo- 
roform, a patient w r ill sometimes suddenly stop breathing, 
apparently because the medulla oblongata becomes affected. 

In another volume, we have insisted upon the mechan- 
ism of the reflex phenomena of respiration. AYe have con- 
clusively shown by experiments, that an impression is re- 
ceived by the sensory nerves of the general system, due to 
want of oxygen, and not to the irritation produced by carbon- 
ic acid ; and that this impression is conveyed to the medulla 
oblongata, and gives rise to the reflex movements of respira- 
tion. If this impression be abolished, there are no respira- 
tory movements ; and if the medulla, the sole centre capable 
of receiving this impression and of generating the stimulus 
sent to the respiratory muscles, be destroyed, respiration in- 
stantly ceases, without any sensation of asphyxia. 1 

It does not seem that there can be any doubt with regard 
to the action of the medulla oblongata as the respiratory 
nervous centre ; still, it has been stated by Brown-Sequard, 
that the commonly-accepted view is not correct ; that the 
sudden arrest of respiratory movements following destruc- 
tion of the medulla is due to irritation and not to its re- 
moval ; and that, in certain cases, the movements may become 
reestablished after the irritation has subsided. 2 Schiff noted, 
in 1852, that dogs lived for a certain time after injury of 

1 See vol. i., Respiration, p. 479, et seq. 

Our original experiments on the respiratory sense were made in 1860-'61, 
and published in October, 1861. See Experimental Researches on Points con- 
nected with the Action of the Heart and with Respiration. American Journal of 
the Medical Sciences, Philadelphia, October, 1861. 

2 BROWX-SEQUARD, Recherches snr les causes de mort apres V ablation de la 
partie de la moelle allongee qui a ete nommee point vital. Journal de la physiolo- 
gie^ Paris, 1858, tome i., p. 217, et seq. ; and, Recherches experimentales sur la 
physiologie de la moelle allongee. Ibid., 1860, tome iii., p. 151, et seq. 



MEDULLA OBLOXGATA. 409 

the so-called vital point. 1 As regards the experiments upon 
which the opinion of Brown-Sequard is based, we have only 
to say that, while a return of respiratory movements is per- 
haps possible in certain cold-blooded animals (which will live 
for weeks after extirpation of the medulla, respiring by the 
skin alone) the experiments on rabbits are so extraordinary, 
and the results obtained are so diametrically opposed to 
those of all other observers, that they cannot be accepted 
without full confirmation. As is remarked by Yulpian, if 
the cause of arrest of respiration in the higher animals were 
due, not to removal of the respiratory centre, but to simple 
irritation, these movements should return after the circula- 
tion had been kept up for a time by artificial respiration. 
This never occurs. " The possibility of reflex movements 
remains during all the time of pulmonary insufflation ; but 
the respiratory movements are definitively abolished." 3 We 
must then adhere to the view that the medulla oblongata is 
the centre which presides over the respiratory movements. 

To conclude our history of the influence of the medulla 
on respiration, we have only to refer to an interesting series 
of experiments recently made by Schiff, in which one lateral 
half of the cord just below the medulla, or the lowest part 
of the medulla, was divided. In these experiments, it was 
found that section of the lateral columns at the point of ori- 
gin of the first pair of cervical nerves abolished respiratory 
movements upon the corresponding side of the body. In 
one experiment, the section was made in a dog, and all the 
movements, except those of respiration, remained. The ab- 
domen was opened, and one-half of the diaphragm was seen 
to be entirely passive. In another experiment, exposure of 
the diaphragm did not affect the volume of air inspired, but 
after section of the lateral column on one side, the volume 
of air inspired was diminished by about one-third. 3 

1 SCHIFF, Lehrbuch der Physiologic, Lahr, 1858-'59, S. 323. 

2 VULPIAN, Systeme ncrveux, Paris, 1866, p. 507. 

8 SCHIFF, Einfluss des verlangerten Marks auf die Athmung. Archiv fur die 
ytsammte Physiologic, Bonn, 1870, Bd. iiL, S. 624. 



ilO NERVOUS SYSTEM. 

Vital Point. Since it has been definitely ascertained 
that destruction of a restricted portion of the gray substance 
of the medulla produces instantaneous and permanent arrest 
of the respiratory movements, Flourens and others have 
spoken of this centre as the vital knot, the destruction of 
which is immediately followed by death. "With our present 
knowledge of the properties and functions of the different 
tissues and organs of which the body is composed, it is almost 
unnecessary to present any arguments to show the unphilo- 
sophic character of such a sweeping proposition. We can 
hardly imagine such a thing as instantaneous death of the 
entire organism ; still less can it be assumed that any restrict- 
ed portion of the nervous system is the one essential, vital 
point. Probably a very powerful electric discharge passed 
through the entire cerebro-spinal axis produces the nearest 
approach to instantaneous death of any thing of which we 
have any knowledge ; but, even here, it is by no means cer- 
tain that some parts do but for a time retain their so-called 
vital properties. In apparent death, the nerves and the 
heart may be shown to retain their characteristic proper- 
ties ; the muscles will contract under stimulus, and will ap- 
propriate oxygen and give off carbonic acid, or respire ; the 
glands may be made to secrete, etc. ; and no one can assume 
that, under these conditions, the entire organism is dead. 
We really know of no such thing as death, except as the vari- 
ous tissues and organs which go to make up the entire body 
become so altered as to lose their physiological properties be- 
yond the possibility of restoration ; and this never occurs for 
all parts of the organism in an instant. A person drowned 
may be to all appearances dead, and would certainly die with- 
out measures for restoration ; yet, in such instances, restora- 
tion may be accomplished, the period of apparent death being 
simply a blank, as far as the recollection of the individual is 
concerned. It is as utterly impossible to determine the ex- 
act instant when the vital principle, or whatever it may bo 
called, leaves the body in death, as to indicate the time 



MEDULLA OBLONGATA. 411 

when the organism becomes a living being. Death is noth- 
ing more than a permanent destruction of so-called vital 
physiological properties ; and this occurs successively, and 
at different periods, for different tissues and organs. 

When we see that frogs will live for weeks, and some- 
times for months, after destruction of the medulla oblongata, 
and that, in mammals, by keeping up artificial respiration, 
we can prolong many of the most important functions, as 
the action of the heart, for hours after decapitation, we can 
understand the physiological absurdity of the proposition 
that there is any such thing as a vital point, in the medulla, 
or in any part of the nervous system. 

Connection of the Medulla Oblongata with Various Re- 
flex Acts. There are numerous reflex phenomena that are 
completely under the control of the medulla oblongata as a 
nerve-centre. Among these are the various acts connected 
with respiration, as yawning, coughing, crying, sneezing, etc. 
It also presides over the coordination of the muscles con- 
cerned in expression, and the act of vomiting. We have seen, 
in treating of the pneumogastric nerves, that their galvani- 
zation arrests the action of the heart in diastole, the same 
result follows galvanization of the medulla at the point of 
origin of these nerves. 1 In another volume, we have fully 
discussed the influence of the medulla upon sugar formation 
in the liver, as illustrated by the beautiful experiments of 
Bernard, in which he produced diabetes in animals by irri- 
tating the floor of the fourth ventricle, and the influence of 
this centre upon the quantity and the composition of the 



There is very little to be said concerning certain ganglia 
and other parts of the brain that we have not yet considered. 
The olfactory bulbs, or ganglia, preside over olfaction, and 
will be treated of fully in connection with the special senses. 

1 See page 225. * See vol. iii., Excretion, pp. 172, 323. 



4:12 NERVOUS SYSTEM. 

The pineal gland and the pituitary body, in their structure, 
present a certain resemblance to the ductless glands, and their 
anatomy has been considered in another volume. 1 Passing 
over the purely theoretical views of Galen, "Willis, Descartes, 
and other of the older writers, who had very indefinite ideas 
of the functions of any of the encephalic ganglia, we have 
only to say that the uses of the pineal gland and pituitary 
body in the economy are entirely unknown. The same re- 
mark applies to the corpus callosum, the septum lucidum, 
the ventricles, hippocampi, and various other minor parts 
that are necessarily described in anatomical works. It is 
useless to discuss the early or even the recent speculations 
with regard to the functions of these parts, which are entirely 
unsupported by experimental or pathological facts, and which 
have not advanced our positive knowledge. Most of the 
parts just enumerated have no physiological history. 

Rolling and Turning Movements following Injury of Cer- 
tain Parts of the Encephalon. 

The remarkable movements of rolling and turning, pro- 
duced by section or injury of certain of the commissural 
fibres of the encephalon, are not very important in their 
bearing upon the functions of the brain, and are rather to be 
classed among the curiosities of experimental physiology. 
These movements follow unilateral lesions, and are depend- 
ent, to a certain extent, upon a consequent inequality in 
the power of the muscles on one side, without actual paraly- 
sis. Yulpian enumerates the following parts, injury of 
which, upon one side, in living animals, may determine 
movements of rotation : 

" 1. Cerebral hemispheres ; 

" 2. Corpora striata ; 

" 3. Optic thalami (Flourens, Longet, Schiff) ; 

" 4. Cerebral peduncles (Longet) ; 

" 5. Pons Yarolii ; 

1 See vol. in., Ductless Glands, p. 364. 



BOLLING AND .TURNING MOVEMENTS. 413 

" 6. Tubercula quadrigemina or bigemina (Flourens) ; 

"7. Peduncles of the cerebellum, especially the middle, 
and the lateral portions of the cerebellum (Magendie) ; 

"8. Olivary bodies, restiform bodies (Magendie) ; 

" 9. External part of the anterior pyramids (Magendie) ; 

" 10. Portion of the medulla from which the facial nerve 
arises (Brown-Sequard) ; 

" 11. Optic nerves ; 

" 12. Semicircular canals (Flourens) ; auditory nerve 
(Br o wn-S equard). ' ' 

To the parts above enumerated, Vulpian adds the upper 
part of the cervical portion of the spinal cord. 1 

The movements which follow unilateral injury of the 
parts mentioned above are of two kinds ; viz., rolling of the 
entire body on its longitudinal axis, and turning, always in 
one direction, in a small circle, called by the French the 
movement of manege. They were first observed in dogs by 
Pourfour du Petit, who noted that animals rolled like a ball, 
after section of one lateral half of the cerebellum with the 
root of one of the peduncles ; 2 but later, Magendie 3 and 
Flourens 4 noted the same phenomena. In 1823, a curious 
case of the same kind of movements in the human subject 
was reported by Serres. 5 It is not necessary to cite in detail 
the numerous experiments of this kind, made by Longet, 
Schiff, Brown-Sequard, Yulpian, and others, except as they 
have presented explanations, more or less satisfactory, of the 
phenomena observed. 

A capital point to determine in the phenomena of rolling 
or turning is, whether these movements be due to paralysis 

1 VULPIAX, Systeme nerveux, Paris, 1866, p. 584. 

2 POURFOUR DU PETIT, Nouveau systeme du cerueau. Recueil d' observations 
d'analomie et de chirurgie, Paris, 1766, p. 121. 

3 MAGEXDIE, Jfemoire sur les fondions de quelques parties du sysleme nerveux. 
Journal de physiologic, Paris, 1824, tome iv., p. 399, el seq. 

4 FLOUREXS, Systeme nerveux, Paris, 1842, p. 489. 

5 SERRES, Suite des recherches sur les maladies organiques du cervelet. Journal 
de physiologic, Paris, 1823, tome iii., p. 136. 



414: NEKVOUS SYSTEM. 

or enfeeblement of certain muscles upon one side of the 
body, to a direct or reflex irritation of the parts of the 
nervous system involved, or to all of these causes combined. 
The experiments of Brown-Sequard and others conclusively 
show that the movements may be due to irritation alone, for 
they occur when parts of the encephalon and the upper por- 
tions of the cord are simply pricked, without section of fibres. 1 
When there is extensive division of fibres, it is probable that 
the effects of the enfeeblement of certain muscles are added to 
the phenomena produced by simple irritation. The most 
satisfactory explanation of these movements is the one pro- 
posed by Brown-Sequard, who attributes them to a more or 
less convulsive action of muscles on one side of the body, 
produced by irritation of the nerve-centres. He regards the 
rolling as simply an exaggeration of the turning movements, 
and places both in the same category. 3 It is proper to state, 
however, that this explanation is not accepted by Longet 3 or 
by Vulpian, 4 both of whom have made numerous experiments 
with regard to the movements of rotation. In addition to 
the phenomena just described, Magendie has noted remark- 
able movements of the eyes following section of one of 
the peduncles of the cerebellum. " The eye of the side op- 
erated upon is directed downward and forward : that of the 
opposite side is fixed in a direction upward and backward, 
which gives to the face a curious expression." 5 Longet 
noted the same phenomena in dogs and rabbits after division 
of one of the restiform bodies. 6 

1 BROWN-SEQUARD, On Turning and Rolling produced by Injuries of the 
Nervous System. Experimental Researches applied to Physiology and Pathology, 
New York, 1853, p. 21. 

2 BROWN-SEQUARD, Note sur les mouvements rotatoires. Journal de la physi- 
ologie, Paris, 1860, tome Hi., p. 720. 

3 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 397, ft seq. 

4 VULPIAN, Systeme nerveux, Paris, 1866, p. 594. 

5 MAGENDIE, Lecons sur les fonctions et les maladies du systeme nerveux, Paris, 
1841, tome i., p. 261. 

6 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 392. 



ROLLING AND TURNING MOVEMENTS. - 415 

We do not propose to enter into an elaborate discussion of 
the above experiments, for the reason that they do not seem 
to have advanced our positive knowledge of the functions of 
the nerve-centres. In some of them, the movements have 
been observed toward the side operated upon, and in others, 
toward the sound side. These differences probably depend 
upon the fact, that in certain experiments, the fibres are 
involved before their decussation, and in others, after they 
have crossed in the median line. In some instances, the 
movements may be due to a reflex action, from stimulation 
of afferent fibres, and in others, the action of the irritation 
may be direct. Judging from the fact that most of the en- 
cephalic commissural fibres are apparently insensible and 
inexcitable under direct stimulation, it is probable that the 
action is generally reflex. 

Though we have avoided a full discussion of the question 
under consideration, it is one that may be, to some, of con- 
siderable interest, from the remarkable character of the phe- 
nomena observed, and the reader is referred for further in- 
formation to the elaborate chapter on this subject by Yulpian 1 
and a recent article by Onimus. 2 In the latter article, there 
are many curious experiments upon frogs and aquatic birds. 

In concluding the physiological history of the encephalon, 
we have only to refer to the general properties of certain of 
the peduncles. Longet found that direct irritation of the 
superior and the inferior peduncles of the cerebellum, in 
rabbits, produced pain, but the disturbance consequent upon 
exposure of the parts did not allow of any accurate observa- 
tions upon the movements. He says nothing of the general 
properties of the middle peduncles or of the peduncles of the 
cerebrum. 3 

1 VULPIAN, Systeme nerveux, Paris, 1866, p. 583, et seq. 

9 ONIMUS, Recherches experimentales sur les phenomenes consecutifs d I 'ablation 
du cerveau et sur les mouvements de rotation. Journal de fanatomie et de la phy- 
siologic, Paris, 1870-'7l, tome vii., p. 662. 

8 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 398. 
127 



CHAPTER XY. 

SYMPATHETIC NERVOUS SYSTEM. 

General arrangement of the sympathetic system Peculiarities in the intimate 
structure of the sympathetic ganglia and nerves General properties of the 
sympathetic ganglia and nerves Functions of the sympathetic system 
Va so-motor nerves Reflex phenomena operating through the sympathetic 
system Trophic centres and nerves, so called. 

WHILE there are certain points in the physiology of the 
sympathetic nervous system that are perfectly well estab- 
lished, it must be admitted that its functions are, in many 
respects, obscure, and that our positive knowledge of its 
general properties and its relations to the functions of nutri- 
tion, secretion, movements, etc., amounts to comparatively 
little. The very name, sympathetic, is some indication of 
our indefinite ideas with regard to its functions ; but we have 
adopted this name, for the reason that it is the one most 
generally in use, though it has no very exact relation to the 
peculiar functions of the system. It is sometimes called the 
ganglionic nervous system ; but this name is inappropriate, 
as it implies that it alone possesses ganglia. The name of 
the system of organic, or vegetative life is more in accord- 
ance with its general functions ; but this is not so commonly 
used as that of sympathetic system. The older anatomists 
and physiologists called the great cord of this system the 
nervus intercostalis. 

As far as we know, there is no account of the sympathetic 
system, even in the most recent works on physiology or in 
special treatises, a careful study of which does not convey 



SYMPATHETIC NERVOUS SYSTEM. 417 

the idea that there is little else in the literature of the sub- 
ject than controversial questions of priority, etc., in minor 
details, and a few observations, some of them quite unsatis- 
factory, with regard to the effects of the division or galvani- 
zation of sympathetic filaments upon the functions of circu- 
lation, secretion, and animal heat. "We can hardly venture 
to hope that this chapter will be exceptional in this regard, 
unless we pass over very briefly the bibliographical discus- 
sions so elaborately presented by many authors. It is un- 
fortunate that well-ascertained facts, which might be stated 
in a very few pages, should be so largely overshadowed by a 
mass of purely historical details of no great interest. Still, 
we must take the physiological data as we find them, and 
endeavor not to limit the knowledge to be looked for in 
the future, by adopting theories upon insufficient positive 
evidence. 

There are certain important anatomico-physiological ques- 
tions, more or less definitely determined, that have a direct 
bearing upon the functions of the sympathetic system. These 
are the following : Is the sympathetic anatomically and physi- 
ologically dependent upon its connections with the cerebro- 
spinal nerves ? What are the general properties of the sym- 
pathetic nerves as regards motion and sensation ? Do the 
sympathetic ganglia act as independent reflex nerve-centres ? 
To what extent and in what way do the sympathetic gan- 
glia and nerves influence the functions of the various organs 
and tissues to which their filaments are distributed ? A so- 
lution of these questions involves a careful and critical study 
of the results of experiments on living animals and of patho- 
logical facts ; and it is evident that very little information 
is to be derived from observations made anterior to the dis- 
covery of the properties and functions of the most important 
parts of the cerebro-spinal system. We will begin the study 
of these points with an account of the general arrangement 
and the peculiarities of structure of the sympathetic ganglia 
and nerves. 



4:18 NERVOUS SYSTEM. 

General Arrangement of the Sympathetic System. 

Like the cerebro-spinal system, the sympathetic is com- 
posed of centres and nerves, at least as far as we can judge 
from its anatomy. The centres contain nerve-cells, most of 
which differ but little from the cells of the encephalon and 
spinal cord. The nerves are composed of fibres, the greater 
part of which are identical in structure with the ordinary 
motor and sensory fibres. The fibres are connected with 
the nerve-cells in the ganglia, and the ganglia are connected 
with each other by commissural fibres. These ganglia con- 
stitute a continuous double chain, on either side of the body, 
beginning above, by the ophthalmic ganglia, and termina- 
ting below, in the ganglion impar. It is important to note, 
however, that, the chain of sympathetic ganglia is not inde- 
pendent, but that each ganglion receives motor and sensory 
filaments from the cerebro-spinal nerves, and that some fila- 
ments pass from the sympathetic to the cerebro-spinal cen- 
tres. The general distribution of the sympathetic filaments 
is to mucous membranes, and possibly to integument, to 
non-striated muscular fibres, and particularly to the muscu- 
lar coat of the arteries. As far as we have been able to 
learn from anatomical investigations, there are no fibres de- 
rived exclusively from the sympathetic which are distributed 
to striated muscles, except those which pass to the muscular 
tissue of the heart. Near the terminal filaments of the sym- 
pathetic, in most of the parts to which these fibres are dis- 
tributed, there exist numerous ganglionic cells. 

The general arrangement of the sympathetic ganglia and 
the 'distribution of the nerves may be stated, sufficiently for 
our purposes, very briefly ; still, a knowledge of certain ana- 
tomical points 'is indispensable as an introduction to an in- 
telligent study of the physiology of this system. 

In the cranium, are four ganglia; the ophthalmic, the 
spheno-palatine, the otic, and the submaxillary. In the neck, 
are the three cervical ganglia ; the superior, middle, and in- 



SYMPATHETIC NERVOUS SYSTEM. 419 

ferior. n the chest, are the twelve thoracic ganglia, corre- 
sponding to the twelve ribs. ' The great semilunar ganglia, 
the largest of all, sometimes called the abdominal brain, are 
in the abdomen, by the side of the coeliac axis. In the lum- 
bar region, in front of the spinal column, are the four, and 
sometimes five, lumbar ganglia. In front of the sacrum, are 
the four or five sacral, or pelvic ganglia ; and in front of the 
coccyx, is a small, single ganglion, the last of the -chain, 
called the ganglion impar. Thus, the sympathetic cord, as 
it is sometimes called, consists of from twenty-eight to thirty 
ganglia on either side, terminating below in a single ganglion. 

Cranial Ganglia. The ophthalmic, lenticular, or ciliary 
ganglion is situated deeply in the orbit, is of a reddish color, 
and about the size of a pin's-head. It receives a motor 
branch from the third pair, and sensory filaments from the 
nasal branch of the ophthalmic division of the fifth. It is 
also connected with the cavernous plexus and with Meckel's 
ganglion. Its so-called motor and sensory roots from the 
third and the fifth pair have already been described in con- 
nection with these nerves. Its filaments of distribution are 
the ten or twelve short ciliary nerves, which pass to the 
ciliary muscle and the iris. A very delicate filament from 
this ganglion passes to the eye with the central artery of the 
retina, in the canal in the centre of the optic nerve. 

The functions of the ophthalmic ganglion are connected 
exclusively with the action of the ciliary muscle and iris ; 
and we will here do nothing more than indicate its anatomi- 
cal relations, leaving its physiology to be taken up under the 
head of vision. 

The spheno-palatine ganglion was first described by 
Meckel, and is known as Meckel's ganglion. 1 This is the 
largest of the cranial ganglia. It is of a triangular shape, 

1 MECKEL, De Ganglia secundi Rami quinti Paris Nervorum Cerebri nuper 
detecto, Herolini, 1749 ; in LUDWIG, Scriptores Nevrofogici min&res selecti, Lipsiae, 
1795, tomus iv., p. 7. 



4:20 . NERVOUS SYSTEM. 

reddish in color, and is situated in the spheno-maxillary fossa, 
near the spheno-palatine foramen. It receives a motor root 
from the facial, by the Yidian nerve. Its sensory roots are 
the two spheno-palatine branches from the superior maxillary 
division of the fifth. Its branches of distribution are quite 
numerous. Two or three delicate filaments enter the orbit 
and go to its periosteum. Its other branches, which it is 
unnecessary to describe fully in detail, are distributed to the 
gums, the membrane covering the hard palate, the soft pal- 
ate, the uvula, the roof of the mouth, the tonsils, the mucous 
membrane of the nose, the middle auditory meatus, a por- 
tion of the pharyngeal mucous membrane, and the levator 
palati and azygos uvulae muscles. It is probable that the 
filaments sent to these two striated muscles are derived from 
the facial nerve and do not properly belong to the sympa- 
thetic system. 1 They were first accurately described, with 
their connections, by Longet. 2 The ganglion also sends a 
short branch, of a reddish-gray color, to the carotid plexus. 

The otic ganglion, sometimes called Arnold's ganglion, 
is a small, oval, reddish-gray mass, situated just below the 
foramen ovale. It receives a motor filament from the facial, 
and sensory filaments from branches of the fifth and the 
glosso-pharyngeal. Its filaments of distribution go to the mu- 
cous membrane of the tympanic cavity and Eustachian tube, 
and to the tensor tympani and tensor palati muscles. Reason- 
ing from the general mode of distribution of the sympathetic 
filaments, those going to the striated muscles are derived 
from the facial. 3 It also sends branches to the carotid plexus. 

The submaxillary ganglion was discovered by Meckel. 4 

1 In treating of the facial (see page 161), we have shown that the movements 
of the levator palati and azygos uvulae are animated by filaments derived from 
this nerve, which simply pass through Meckel's ganglion. 

2 LONGET, Anatomic et physiologic du systeme nerveux, Paris, 1842, tome ii., 
p. 128. 

3 See page 154. 

4 MECKEL, De quinto Pare Nervorum Cerebri ; in LUDWIG, Scriptores Nevro- 
logici minorcs selecti, Lipsiae, 1791, tomus L, p. 214. 



SYMPATHETIC NEKVOTTS SYSTEM. 4:21 

It is situated on the submaxillary gland, is small, rounded, 
and of a reddish-gray color. It receives motor filaments from 
the chorda tympani, and sensory filaments from the lingual 
branch of the fifth. Its filaments of distribution go to "Whar- 
ton's duct, to the mucous membrane of the mouth, and to 
the submaxillary gland. 

Cervical Ganglia. The three cervical ganglia are situ- 
ated opposite the third, fifth, and the seventh cervical ver- 
tebrae respectively. The middle ganglion is sometimes 
wanting, and the inferior is occasionally fused with the first 
thoracic ganglion. These ganglia are connected together 
by the so-called sympathetic cord. They have numerous 
filaments of communication above, with the cranial and the 
cervical nerves of the cerebro-spinal system. Branches from 
the superior ganglion go to the internal carotid, to form the 
carotid and the cavernous plexus, following the vessels as 
they branch to their distribution. Branches from this gan- 
glion pass to the cranial ganglia. There are also branches 
which unite with filaments from the pneumogastric and 
the glosso-pharyngeal to form the pharyngeal plexus, and 
branches which form a plexus on the external carotid, the 
vertebral, and the thyroid artery, following the ramifications 
of these vessels. 

From the cervical portion of the sympathetic, the three 
cardiac nerves arise and pass to the heart, entering into the 
formation of the cardiac plexus. The superior cardiac nerve 
arises from the superior ganglion ; the middle nerve, the 
largest of the three, arises from the middle ganglion, or from 
the sympathetic cord, when this ganglion is wanting ; and 
the inferior nerve arises from the inferior ganglion or the first 
thoracic. These nerves present numerous communications 
with various of the adjacent cerebro-spinal nerves, penetrate 
the thorax, and form the deep and the superficial cardiac 
plexus, and the posterior and the anterior coronary plexus. 
In these various plexuses, are found numerous ganglioform 



422 NEKVOTJS SYSTEM. 

enlargements ; and upon the surface and in the substance 
of the heart, are numerous collections of nerve-cells con- 
nected with the fibres, which were first accurately described 
and figured by Dr. Robert Lee. 1 

Thoracic Ganglia. The thoracic ganglia are situated in 
the chest, under the pleura, and rest on the heads of the 
ribs. They are usually twelve in number, but occasionally 
two are fused into one. They are connected together by 
the sympathetic cord. They each communicate by two fila- 
ments with the cerebro-spinal nerves ; one of these being 
white, like the spinal nerves, and probably passing to the 
sympathetic, and the other, of a grayish color, is thought to 
contain the true sympathetic filaments. From the upper six 
ganglia, filaments pass to the aorta and its branches. The 
branches which form the posterior pulmonary plexus arise 
from the third and fourth ganglia. The great splanchnic 
nerve arises mainly from the seventh, eighth, and ninth 
ganglia, receiving a few filaments from the upper six gan- 
glia. This is a large, white, rounded cord, which penetrates 
the diaphragm and passes to the semilunar ganglion, send- 
ing a few filaments to the renal plexus and the suprarenal 
capsules. The lesser splanchnic nerve arises from the tenth 
and eleventh ganglia, passes into the abdomen, and joins the 
coeliac plexus. The renal splanchnic nerve arises from the 
last thoracic ganglion, and passes to the renal plexus. The 
three splanchnic nerves present numerous anastomoses with 
each other. 

Ganglia in the Abdominal and the Pelvic Cavity. 
The semilunar ganglia on the two sides send off radiating 
branches to form the solar plexus. They are situated by 
the side of the coeliac axis and near the suprarenal cap- 
sules. These are the largest of the sympathetic ganglia. 
From these arise numerous plexuses distributed to various 

1 LEE, On the Ganglia and Nerves of the Heart. Philosophical Transactions, 
1849, Part i., London, 1849. 



SYMPATHETIC NERVOUS SYSTEM. 423 

parts in the abdomen, as follows : The phrenic plexus follows 
the phrenic artery and its branches, to the diaphragm. The 
coeliac plexus subdivides into the gastric, hepatic, and splenic 
plexuses, which are distributed to organs as their names in- 
dicate. From the solar plexus, different plexuses are given 
off, which pass to the kidneys, the suprarenal capsules, the 
testes, in the male, and the ovaries, in the female, the intes- 
tines, by the superior and the inferior mesenteric plexuses, 
the upper part of the rectum, the abdominal aorta, and the 
vena cava. The filaments follow the distribution of the 
blood-vessels in the solid viscera. 

The lumbar ganglia, four in number, are situated in the 
lumbar region, upon the bodies of the vertebrae. They are 
connected with the ganglia above and below and with each 
other by the sympathetic cord, receiving, like the other gan- 
glia, filaments from the spinal nerves. Their branches of 
distribution form the aortic lumbar plexus and the hypogas- 
tric plexus, and follow the course of the blood-vessels. 

The four or five sacral ganglia and the ganglion impar 
are situated by the inner side of the sacral foramina and in 
front of the coccyx. These are connected with the ganglia 
above and with each other, and receive filaments from the 
sacral nerves, there being generally two branches of com- 
munication for each ganglion. The filaments of distribution 
go to all of the pelvic viscera and the blood-vessels. The 
inferior hypogastric, or pelvic plexus is a continuation of the 
hypogastric plexus above, and receives a few filaments from 
the sacral ganglia. The most interesting branches from this 
plexus are the uterine nerves, which go to the uterus -and 
the Fallopian tubes. In the substance of the uterus, the 
nerves are connected with small collections of ganglionic 
cells, which were described in 1839, by Dr. Robert Lee. 1 
The sympathetic filaments are undoubtedly prolonged into 
the upper and lower extremities, following the course of the 
blood-vessels, and are distributed to their muscular coat. 

LEE, Memoir on the Ganglia and Nerves of the Uterus, London, 1849. 



424: NEKVOTJS SYSTEM. 

According to the latest researches, the filaments of the 
sympathetic, at or near their termination, are connected with 
ganglionic cells, not only in the heart and the uterus, but in 
the blood-vessels, lymphatics, anal canals, the submucous and 
the muscular layer of the entire alimentary canal, the sali- 
vary glands, liver, pancreas, larynx, trachea, pulmonary tis- 
sue, bladder, ureters, the entire generative apparatus, supra- 
renal capsules, thymus, lachrymal canals, ciliary muscle, and 
the iris. 1 In these situations, nerve-cells have been demon- 
strated by various observers, and it is probable that they 
exist everywhere in connection with the terminal filaments 
of this system of nerves. 

Peculiarities in the Intimate Structure of tJie Sympa- 
thetic Ganglia and Nerves. The peculiarities in the struct- 
ure of the cells and fibres of the sympathetic system are 
not numerous, nor do they possess very great physiological 
importance. The free communications between the sympa- 
thetic ganglia and the cerebro-spinal nerves, and the differ- 
ences in the general appearance of certain of these anasto- 
mosing branches, lead to the important question of their 
origin. As a rule, the sympathetic nerves are softer and 
more grayish in color than the spinal nerves. When there 
are two branches of communication between a ganglion and 
a spinal nerve, one of them is white and the other is gray- 
ish, and we might infer from this that one, the white, is 
derived from the spinal system, and the other, from the sym- 
pathetic ; but this is a point not yet settled by microscopical 
investigations. It has been conclusively shown, however, 
by Courvoisier, that the communicating fibres pass in both 
directions. Taking advantage of the degeneration of nerve- 
fibres after separation from their proper centres, this ob- 
server has demonstrated that, after division of the branches 
between the spinal nerves and the sympathetic ganglia, cer- 

1 MATER, in STRICKER, Handbuch der Lelire von den Geweben, Leipzig, 1871, 
S. 820. 



SYMPATHETIC NERVOUG SYSTEM. 425 

tain fibres in the end attached to the spinal . nerve become 
degenerated, while others retain their anatomical integrity. 
This shows that, in all probability, the cells to which the 
degenerated fibres belong are in the sympathetic ganglia, 
and that the perfect fibres belong to the cerebro-spinal sys- 
tem. On the other hand, in the end attached to the sympa- 
thetic ganglia, there are degenerated fibres which belong 
to the spinal system, and perfect fibres attached to the sym- 
pathetic cells. According to these observations, in frogs, 
the fibres belonging to the spinal nerves constitute about 
two-thirds of the communicating branches, one-third being 
derived from the sympathetic system. In rabbits, the pre- 
ponderance of the cerebro-spinal fibres is not so great. 1 

While the branches of the sympathetic contain a large 
number of the ordinary medullated fibres, such as are found 
in the cerebro-spinal nerves, they also present numerous 
fibres of Remalc, and fine fibres, from 10 ^ 00 to 6 ^ QO of an 
inch in diameter, which are regarded by Kolliker as true 
efferent fibres from the sympathetic ganglia. 2 "With regard 
to the fibres of Reinak, we have nothing to add to what we 
have already stated under the head of the general structure 
of the nervous system. 3 These points, with the fact that 
most of the terminal filaments of the sympathetic are con- 
nected with nerve-cells in the substance of the different tis- 
sues, constitute the most important anatomical peculiarities 
of the sympathetic nerve-fibres. 

With regard to the cells, which constitute the character- 
istic anatomical element of the sympathetic ganglia, we shall 
have little to say, as their peculiarities at present seem to be 
of purely anatomical interest. They are generally rounded, 
ovoid, or pear-shaped, with a nucleus, generally clear, and a 

1 COURVOISIER, Beobacldungen tiber den sympathvsclien Qrranzstrang. Archiv 
fur microscopische Anatomic, Bonn, 1866, Bd. ii., S. 30, et seq. The method 
adopted in these investigations is the one already referred to, employed by "Wal- 
ler. (See page 80.) 

8 KOLLIKER, Elements d'histologie humaine, Paris, 1868, p. 426. 

3 See page 24. 



426 NERVOUS SYSTEM. 

distinct nucleolus. They present a nucleated capsule, prob- 
ably composed of connective tissue, which is sometimes lined 
on its inner surface with a single layer of flattened, polygo- 
nal epithelium. Some of the cells are unipolar, some are 
bipolar, and some are multipolar. In frogs, Beale and Ar- 
nold have described a peculiar appearance in certain cells, 
there being a single, straight prolongation, surrounded by a 
fine, spiral fibre. These have not been demonstrated in the 
human subject, and it is not necessary to enter into a discus- 
sion of the probable origin and nature of the spiral fibre. 1 
The connection between the cells and fibres of the sympa- 
thetic is probably the same as in the cerebro-spinal centres, 
and is represented in the accompanying diagram, taken from 
Leydig. 

FIG. 11. 




Sympathetic ganglion with multipolar cells ; highly magnified. (LEYDIG, Traite ffhistologie, 
Paris, 1866, p. 193.) 



General Properties of the Sympathetic Ganglia and Nerves. 

The older writers had no definite ideas with regard to the 
functions of the sympathetic system, and were divided, even, 
on the simple question of its sensibility, some assuming that 

1 For a full account of the spiral fibres and the peculiarities of structure of 
the sympathetic system, the reader is referred to the elaborate article by Mayer. 
(STRICKER, Handbuch der Lehre von den Geweben, Leipzig, 1871, S. 815.) 



SYMPATHETIC NERVOUS SYSTEM. 427 

the ganglia were absolutely insensible, while others noted 
distinct evidences of pain following their irritation in living 
animals. Passing to the researches of the more recent ob- 
servers, we find that Flourens noted evidences of pain on 
pinching the semilunar ganglia, in rabbits. 1 Brachet ex- 
posed the abdominal and the thoracic ganglia in calves, dogs, 
etc., and found them at first insensible, but pricking these 
pails produced pain after they had been exposed for a few 
minutes. The sensibility thus noted was thought by Brachet 
to be due to inflammation following exposure of the gan- 
glia. 2 Miiller found that mechanical or chemical irritation 
of the semilunar ganglia in rabbits produced pain. 3 With- 
out discussing the observations of Bichat * and others, who 
regarded the sympathetic ganglia and nerves as entirely in- 
sensible, we will pass to the direct experiments of Longet, 
the results of which seem to be entirely trustworthy and 
satisfactory, both as regards sensibility and the property of 
exciting movements. In all experiments of this kind, it is 
of course essential to avoid direct irritation or traction of 
the communicating branches from the cerebro-spinal nerves. 
In dogs, Longet noted distinct evidences of sensibility fol- 
lowing irritation of the semilunar ganglia, and pain after 
prolonged stimulation of the ganglia in the cervical and in 
the lumbar region, taking all precautions to avoid irritating 
the cerebro-spinal filaments. The sensibility of these parts, 
however, is dull as compared with that of the ordinary sen- 
sory nerves. 6 We have also noted a dull but well-marked 
sensibility of the cervical ganglia in rabbits. In view of the 
decided and uniform results of the most careful recent ex- 
periments on this point, there can be no doubt of the exist- 

1 FLOUREXS, Recherches experimentales sur lex proprietes d les f emotions du 
systeme nerveux, Paris, 1842, p. 230. 

2 BRACKET, Recherches experimentales sur les fonctions du systeme ncrveux 
yanglionaire, Bruxelles, 1834, p. 305, ei seq. 

3 MULLER, Elements of Physiology, London, 1840, vol. L, p. 712. 

4 BICHAT, Anatomic generale, Paris, 1801, tome L, p. 227. 

5 LOXGET, Traite de phi-siologie, Paris, 1869, tome iii., p, 593. 



4:28 NERVOUS SYSTEM. 

ence of a certain degree of sensibility in the ganglia of the 
sympathetic system. 

As regards excitability, recent experiments are quite 
satisfactory. Miiller exposed the intestines and the semi- 
lunar ganglia in rabbits ; and, having waited until the intes- 
tines, which generally present movements on first opening 
the abdomen, had ceased their contractions, the peristaltic 
movements " were immediately renewed with extraordinary 
activity " by touching the ganglia with caustic potash. 1 The 
experiments of Longet show that a feeble continued galvanic 
current applied to the great splanchnic nerves produces con- 
tractions of the muscular coat of the intestines, when they 
contain alimentary matters, but that no contractions occur 
when they are empty. a On the other hand, Pniiger has ob- 
served that galvanization of the splanchnic nerves produces 
a passive condition of the small intestine ; that is, arrest of 
its movements without persistent contractions of its muscu- 
lar coat ; but these results were not confirmed in analogous 
experiments performed by Biffi. 8 More recently, in a series 
of very elaborate experiments, by Legros and Onimus, it has 
been shown that the induced galvanic current applied to the 
splanchnic nerves does not produce peristaltic movements, but 
that these movements are excited by the constant current. 4 

Taking into consideration the most reliable direct obser- 
vations upon the sympathetic ganglia and nerves, the fact 
that their stimulation induces movements in the non-striated 
muscles to which they are distributed can hardly be doubted. 
This action is particularly well marked in the muscular coat 
of the blood-vessels ; but here, the function of the nerves is 
so important, that it merits special consideration, and will 

1 MiJLLER, Elements of Physiology, London, 1840, vol. i., p. 713. 

2 LONGET, Traite de phyisologie, Paris, 1869, tome iii., p. 595 ; and, Anatomie 
ct physiologic du systeme nerveux, Paris, 1842, tome ii., p. 568. 

3 PFLUGER ET BIFFI, Sur une systeme qui suspend les mouvemcnts de Pintestin 
grele. Journal de la physiologic, Paris, 1858, tome i., p. 421. 

4 LEGROS ET ONIMUS, Recherches experimentales sur les mouvements de Vintestin. 
Journal de I'anatomie, Paris, 1869, tome vi., p. 196. 



SYMPATHETIC NERVOUS SYSTEM. 429 

be treated of fully under the head of the vaso-motor nerves. 
The mechanism of these movements, however, is peculiar. 
The action does not immediately follow the stimulation, as 
it does in the case of the cerebro-spinal nerves and the striated 
muscles, but is induced gradually, beginning a few seconds 
after the irritation, endures for a time, and is more or less 
tetanic. 1 This mode of action is peculiar to the sympathetic 
nerves and the non-striated muscular fibres. 

"When we remember the invariable connection of the 
sympathetic ganglia with the cerebro-spinal nerves, we see 
at once the importance of the question of the derivation of 
the motor and sensory properties of the ganglionic system. 
Are the sympathetic ganglia independent nerve-centres, or do 
they derive their properties from the cerebro-spinal system ? 
This question may be satisfactorily answered by two kinds 
of experimental facts : In the first place, section or irritation 
of the spinal cord and certain of the encephalic centres is 
capable of influencing the vaso-motor system, a fact which 
will be dwelt upon more fully in another connection. In 
the second place, the experiments of Bernard upon the sub- 
maxillary ganglion and its influence on the secretion of the 
submaxillary gland have demonstrated, in the most conclu- 
sive manner, that this ganglion is the centre presiding imme- 
diately over the reflex phenomena of secretion by the gland ; 
but it has also been shown that, when all of the connections 
of the submaxillary ganglion with the cerebro-spinal system 
are divided, after a few days, this ganglion loses its power as 
a reflex nervous centre. 8 In the volume on secretion, we 
have given numerous examples of reflex action through the 
sympathetic system. 3 The experiments just cited from Ber- 
nard show that individual ganglia belonging to this system 
may act independently for a time ; but that this action can- 

1 LEGROS ET OXIMUS, De la contraction des muscles de la vie vegetative. 
Journal de V anatomic, Paris, 1869, tome vi., p. 433. 

8 BERNARD, RecJierches experimentales sur les nerfs vasculaires et cahrifiques. 
Journal de la physiologic, Paris, 1862, tome v., pp. 407, 410. 

8 See vol. iii., Secretion, p. 28, et seq. 



430 NERVOUS SYSTEM. 

not remain indefinitely, after the cerebro-spinal branches 
have been divided. It remains, however, to apply these ex- 
periments to other sympathetic ganglia ; but, in the case of 
the snbmaxillary, they are very satisfactory, from the facility 
with which the parts may be operated upon, and the certainty 
with which the ganglion may be separated from its connec- 
tions with the cerebro-spinal system. As regards the ex- 
planation of the final loss of power over the functions of the 
snbmaxillary gland, the experiments of Waller seem to have 
escaped the attention of the eminent physiologist whom we 
have quoted. There is no experimental fact more conclu- 
sively demonstrated than that of the anatomical degeneration 
and consequent loss of physiological function of nerve-fibres 
in a few days after they have been separated from their cen- 
tres of origin. After division of a cerebro-spinal nerve-trunk, 
the tubes soon lose their anatomical characters, and will no 
longer respond to a galvanic stimulus. In the case of the 
fibres operating upon the submaxillary gland, the question 
of their degeneration after division of the cerebro-spinal 
roots was not submitted to microscopical investigation. If 
these fibres had undergone the degeneration which has so 
frequently been observed in experiments upon other nerves, 
their galvanization would not have produced any effect ; 
which was precisely the result obtained by Bernard. In the 
absence of direct observations upon this point, it is the most 
reasonable view to adopt, that the fibres from the cerebro- 
spinal nerves had lost their function, as a natural consequence 
of separation from their centres, and that this was the cause 
of the absence of effect upon the gland following their gal- 
vanization. The observation of Bernard shows, however, 
that filaments may pass to special organs from the cerebro- 
spinal centres through the sympathetic ganglia. 

Functions of the Sympathetic System. 

In the earfy part of the last century (1712 and 1725), 
Pourfour du Petit demonstrated that the influence of the 



FUNCTIONS OF THE SYMPATHETIC SYSTEM. 431 

sympathetic nerve in the neck (the great sympathetic was 
frequently called the nervus intercostalis) was propagated 
from below upward toward the head, and not from the brain 
downward. This may be taken as the starting-point of our 
definite knowledge of the functions of the sympathetic sys- 
tem, though the experiments of Petit only showed the influ- 
ence of the cervical portion upon the eye. 1 In 1816, Dupuy 
removed the superior cervical ganglia in horses, with the 
effect of producing injection of the conjunctiva, increase of 
temperature in the ear, and an abundant secretion of sweat 
upon one side of the head and neck. 3 These experiments 
showed that the sympathetic has an important influence on 
nutrition, calorification, and secretion. In 1851, Bernard 
repeated the experiments of Pourfour du Petit, dividing the 
sympathetic in the neck on one side in rabbits, and noted, 
on the corresponding side of the head and the ear, increased 
vascularity, and an elevation in temperature, amounting to 
from 7 to 11 Fahr. This condition of increased heat and 
vascularity continues for several months after division of the 
nerve. 3 In 1S52, Brown-Sequard repeated these experiments, 

1 PETIT, Memoire dans lequel il est demonlre que les nerfs intercostaux four- 
nissent des rameaux qui portent dts esprits dans les yeux. Memoires de Vacademie 
royale des sciences, Annee 1727, Paris, 1729, p. 5, et seq. 

2 DUPCY, Versuche iiber die Wegnahme des ersten Halsknolens des Ganglionner- 
ven bd Pferden (Aus Leroux's Journ. de Medec., t. xxxvii., 1816, pp 340-350). 
Deutschcs Archiv fur die Physiologic, Halle und Berlin, 1818, Bd. iv., S. 105, et 
seq. 

We have been unable to consult the article by Dupuy in the original, but the 
reference in Meckel's Archiv gives a full account of the experiments and conclu- 
sions. In one experiment, it is stated that, after removal of the ganglia on both 
sides, in a horse, already feeble and emaciated, the face and ears became hot 
and moist. Dupuy does not seem to have attached much importance to the ele- 
vation in temperature. In his conclusions, he states that " the consequences 
of destruction of the ganglia are, constriction of the pupils, redness of the con- 
junctiva, general emaciation, as well as oedema of the extremities and a general 
cutaneous eruption. The ganglionic nerve appears to have a great influence 
upon nutrition." 

3 BERNARD, Influence du grand sympathique sur la sensibilite et sur la calorifi- 
cation. Complex nndus de la societe de biologie, Paris, 1851, tome iii., p. 163. 

128 



432 NERVOUS SYSTEM. 

and attributed the elevation of temperature directly to an 
increase in the supply of blood to the parts affected. He 
made a most important advance in the history of the sympa- 
thetic, by demonstrating that its section paralyzed the mus- 
cular walls of the arteries, and, farther, that galvanization 
of the nerve in the neck caused the vessels to contract. This 
was the discovery of the vaso-motor nerves, concerning which 
so much has been written within the past few years, and 
it belongs without question to Brown-Sequard, who published 
his observations in August, 1852. 1 A few months later, in 
the same year, Bernard made analogous experiments, and 
presented the same explanation of the phenomena observed. 3 

The above embraces all that is important with regard to 
the history of experimental observations upon the sympa- 
thetic. It is evident that we could know nothing of the 
functions of this system before the time of Pourfour du 
Petit, when the prevailing opinion was that the nerve origi- 
nated from the encephalon, and that its influence was propa- 
gated downward; and the writings of Bichat, Brachet, Tie- 
demann, and others, published anterior to the experiments 
of Bernard and of Brown-Sequard, present interesting sug- 
gestions and theories, but contain little that bears upon our 
positive knowledge. 

The important points developed by the first experiments 
of Bernard and of Brown-Sequard were, that the sympathetic 
influences the general process of nutrition, and that many 
of its filaments are distributed to the muscular coat of the 
blood-vessels. Before these experiments, it had been shown 
that filaments from this system influenced the contractions 

1 BROWN-SEQUARD, Experimental Researches applied to Physiology and Pathol- 
ogy. The Medical Examiner, Philadelphia, August, 1852, New Series, vol. viii., 
p. 489. In 1839, Valentin referred to filaments of the sympathetic distributed 
to the blood-vessels and influencing their calibre {VALENTIN, De Functionibus 
Nervorum Cerebralium et Nervi Sympathetici, Bernae, 1839, p. 153, et seq.). 

2 BERNARD, Sur les cffets de la section de la portion cephalique du grand sinn- 
pathique. Compte rendu des seances de la societe de biologic pendant le mois de 
novembre, Paris, 1852, tome iv., p. 169. 



FUNCTIONS OF THE SYMPATHETIC SYSTEM. 433 

of the muscular coats of the alimentary canal. Leaving, for 
the present, the action of the vaso-motor nerves, we will 
briefly recapitulate some of the facts with regard to the in- 
fluence of the sympathetic upon animal heat and secretion. 

AVhen the sympathetic is divided in the neck, the local 
increase in temperature is always attended with a very great 
increase in the supply of blood to the side of the head corre- 
sponding to the section. The increased temperature is due 
to a local exaggeration of the nutritive processes, apparently 
dependent directly upon the hypersemia ; and it is not prob- 
able that there are any nerves to which the n^me of calorific, 
as distinguished from yaso-motor, can justly be applied. 
There are numerous instances in pathology of local increase 
in temperature attending increased supply of blood to re- 
stricted parts. 

The experiment of dividing the sympathetic in the neck, 
especially in rabbits, is so easily performed, that the phenom- 
ena observed by Bernard and Brown- Sequard have been re- 
peatedly verified. We have often done this in class-demon- 
strations. A very striking experiment is the following, sug- 
gested by Bernard : 1 After dividing the sympathetic arid ex- 
hibiting the increase in the temperature and the vascularity 
of the ear on one side in the rabbit, if both ears be cut off 
just above the head with a sharp knife, the artery on the 
side on which the sympathetic has been divided will fre- 
quently send up a jet of blood to the height of several feet, 
while, on the sound side, the jet is always much less forcible, 
and may not be observed at all. This experiment succeeds 
best in large rabbits. 

It is very easy to observe the effects of dividing the 
sympathetic in the neck, but analogous phenomena have been 
npted in other parts. Among the most striking of these 
experiments are those reported by Samuel, who noted an 
intense hyperaemia of the mucous membrane of the stomach 

1 BERNARD, Rechcrches experimentales sur les nerfs vascidaires et calorifiqucs 
du grand sympathique. Journal de la physiologic, Paris, 1862, tome v., p. 397. 



4:34 NERVOUS SYSTEM. 

and intestines following extirpation of the coeliac plexus. By 
comparative experiments, it was shown that this did not re- 
sult from the peritonitis produced by the operation. 1 

As regards secretion, the influence of the sympathetic is 
very marked. When the sympathetic filaments distributed 
to a gland are divided, the supply of blood is very much in- 
creased, and an abundant flow of the secretion follows. This 
point we have already discussed in another volume, and have 
referred particularly to the experiments of Bernard upon the 
salivary glands. 3 In some recent experiments by Peyrani, 
it has been shown that the sympathetic has a remarkable in- 
fluence over the secretion of urine. "When the nerves are 
galvanized in the neck, the amount of urine and urea is in- 
creased, and this increase is greater with the induced than 
with the constant current. "When the sympathetic is divided, 
the quantity of urine and urea sinks to the minimum. 3 

Since the publication of our volume on secretion, Dr. 
Moreau has published a series of observations on the influ- 
ence of the sympathetic nerves upon the secretion of liquid 
by the intestinal canal, which are peculiarly interesting in 
their bearing upon the sudden occurrence of watery diar- 
rhoea. In these experiments, the abdomen was opened in a 
fasting animal, and three loops of intestine, each from four to 
eight inches long, were isolated by two ligatures. All of 
the nerves passing to the middle loop were divided, taking 
care to avoid the blood-vessels. The intestine was then 
replaced, and the wound in the abdomen was closed with 
sutures. The next day the animal was killed. The two 
loops with the nerves intact were found empty, as is normal 
in fasting animals, and the mucous membrane was dry ; but 
the loop with the nerves divided was found filled with a 

1 SAMUEL, Principes fondamentaux de Vhistoire du systeme ncrveux nutritif. 
Journal de la physiologic, Paris, 1860, tome iii., p. 580. 

2 See vol. iii., Secretion, p. 28, et seq. 

3 PEYRAXI, Le sympafhique par rapport d la secretion des urines. Complex 
rendus, Paris, 1870, tome Ixf., p. 1300. 



FUNCTIONS OF THE SYMPATHETIC SYSTEM. 435 

clear, alkaline liquid, colorless or slightly opaline, which pre- 
cipitated a few flocculi of organic matter on boiling. 1 

Vaso-Motor Nerves. 

The experiments which we have already cited demonstrate} 
beyond a doubt the existence of nerves distributed to the 
muscular coats of the blood-vessels, and capable of regulating 
their calibre and the quantity of blood sent to different parts. 
These are the vaso-motor nerves, discovered by Brown-Se- 
quard, in 1S52. 2 The importance of nerves capable of regu- 
lating what we may call the local circulations is sufficiently 
apparent. The glands, for example, require at certain times 
an immense increase in their supply of blood, and the same 
is probably true of the muscles, brain, and other parts. It 
has been shown, by direct experiments upon living animals, 
that local variations in the circulation, independent of the 
action of the heart, actually take place, and that they are of 
great importance in special functions ; and there are nu- 
merous instances of such action, which can only take place 
through the nervous system. The phenomena of blushing 
and pallor, from mental emotions, are familiar examples. 

There can be no doubt of the fact that the sympathetic 
branches contain filaments capable of modifying the calibre 
of the blood-vessels, and that the cerebro-spinal nerves also 
contain elements possessing analogous properties ; but when 
we reflect upon the extensive anastomoses, in both directions, 
between the sympathetic and the ordinary motor and sensory 
nerves, we can appreciate the importance of determining the 
exact origin and course of these vaso-motor fibres. The first 
important question is, whether the vaso-motor filaments be 
derived from the sympathetic ganglia or from the cerebro- 
spinal centres. 

All experiments upon the question just proposed tend to 

1 MOREAU, Experiences physioloyiques sur Vintestin. Bulletin de Tacademie 
imp-.riale de medecine, Paris, 1860, tome xxxv., p. 388. 
8 See page 432. 



4:36 NERVOUS SYSTEM. 

show that the vaso-motor nerves are derived exclusively from 
the cerebro-spinal system, and do not originate in the sym- 
pathetic ganglia. "Without citing the numerous confirmatory 
observations of different physiologists, it is sufficient to state 
that Schiff has experimentally demonstrated, in the most 
conclusive manner, that the vaso-motor nerves are derived 
from the cerebro-spinal centres and not from the sympathetic 
ganglia. 1 There is now no difference of opinion among physi- 
ologists upon this point, the only question being the exact 
location of the vaso-motor centres. Ludwig and Thiry found 
that section of the cord in the upper cervical region produced 
dilatation of most of the blood-vessels of the organism, but 
notably of the mesenteric vessels, and that galvanization of 
the cord at its lower cut extremity caused the vessels to con- 
tract. 2 These observations have been repeatedly confirmed. 
As a summary of our present knowledge of the origin 
of the vaso-motor nerves in the cerebro-spinal axis, we may 
cite the following remarks, from a review of the experiments 
of Schiff, by Brown-Sequard : " 1. That if there are vaso- 
motor elements which decussate in the spinal cord, their 
number is excessively small. 2. That the facts observed 
by M. Schiff, on this subject, admit of a more simple ex- 
planation. 3. That a number of the vaso-motor elements 
stop in the spinal cord. 4. That a tolerably large number 
of vaso-motor elements, coming from different points in the 
body, ascend as far as the tuber annulare, and some as far as 
the cerebellum and to other parts of the encephalon. 5. 
That consequently, the medulla oblongata is not the sole 
source of the vaso-motor elements." 5 These statements 
express pretty much all that we know of the origin of the 
vaso-motor elements and their decussation, as far as their 

1 SCHIFF, JTntersuchungen zur Physiologic des Nerveiisystems, Frankfurt am 
Main, 1855, S. 167, et seq. 

2 LUDWIG UNO THIRY, Uber den Einfiuss dcs Halsmarkes a>if den Blntstrom. 
Sitzungs-berichte der mathematischnaturwissemchaftliclien Classe dcr kaiserlichen 
tlkademie der Wissenschaften, Wien, Bd. xlix., ii Abtheilung, S. 421, et scq. 

3 Journal de la physiologie , Paris, 1858, tome i., p. 214. 



FUNCTIONS OF THE SYMPATHETIC SYSTEM. 437 

direct action is concerned ; but some important points have 
been developed by observations on reflex vaso-motor phenom- 
ena, involving a transmission of impressions to the centres 
through the nerves of general sensibility. 

Reflex Phenomena operating through the Sympathetic 
System. We shall not discuss, in this connection, the reflex 
phenomena of secretion, as these have already been consid- 
ered with sufficient minuteness in another volume, 1 nor 
again treat of reflex action, through the sympathetic, upon 
the general circulatory system, which has been taken up 
fully under the head of the depressor-nerve of the circu- 
lation, described by the brothers Cyon, 2 but shall here de- 
scribe certain reflex acts, involving vaso-motor phenomena, 
which we thus far haA^e touched upon very briefly. 

In treating of animal heat, the phenomena of which are 
intimately connected with the supply of blood to the parts, 
we have mentioned the observations of Brown-Sequard and 
Lombard, who found that pinching of the skin on one side 
was attended with a diminution in the temperature in the 
corresponding member of the opposite side, and that some- 
times, when the irritation was applied to the upper extremi- 
ties, changes were produced in the temperature of the lower 
limbs. Tholozan and Brown-Sequard found, also, that low- 
ering the temperature of one hand produced a considerable 
depression in the heat of the other hand, without any nota- 
ble diminution in the general heat of the body. Brown- 
Sequard showed that by immersing one foot in water at 41 
Fahr., the temperature of the other foot was diminished 
about 7 Fahr. in the course of eight minutes. 3 These facts 
show that certain impressions made upon the sensory nerves 
afiect the animal heat by reflex action. As section of the 
sympathetic filaments increases the heat in particular parts, 
with an increase in the supply of blood, and their galvaniza- 

1 See vol. iii., Secretion, p. 32. 2 See page 229. 

3 See vol. iii., Nutrition, p. 416. 



438 NERVOUS SYSTEM. 

tion reduces the quantity of blood and diminishes the tem- 
perature, it is reasonable to infer that the reflex action takes 
place through the vaso-motor nerves. If we assume that 
the impression is conveyed to the centres by the nerves of 
general sensibility, and that the vessels- are modified in 
their calibre and the heat is affected through the sympathetic 
fibres, we have only to determine the situation of the cen- 
tres which receive the impression and generate the stimulus. 
These centres, as we have already seen, are not located in 
the sympathetic ganglia, but in the cerebro-spinal axis. . 

In this connection, we may quote a curious observation 
by Schiff, which he brings forward to illustrate the influence 
of the brain in certain acts, probably operating through the 
sympathetic system : " It is undisputed that psychical acts 
are determined by the brain. If we bring a dog and a cat 
together, their psychical irritation is manifested more espe 
cially therein that the hair of the dog on his back, of the 
cat on her tail, stands up. Now, if we destroy, in the cat, 
the lumbar portion of the spinal cord, and bring her together 
with, a strange dog, the hair of the tail will still rise. If we 
leave the spinal nerves intact, the hair of the cat's tail will 
remain smooth, even though she be attacked by a dog." l 

From all of these observations, and others of the same 
kind which we have not thought it necessary to quote, the 
existence of vaso-motor nerves and their connection with 
centres in the cerebro-spinal axis are sufficiently well estab- 
lished. It is certain, also, that centres presiding over par- 
ticular functions may be located, as the genito-spinal centre, 
in the spinal cord opposite the fourth lumbar vertebra, and 
the cilio-spinal centre, in the cervical region of the cord, 
both described by Budge. 2 A stimulus generated in these 

1 SCHIFF, The Independence of the Sympathetic. Journal of Psychological 
Ifcdicine, Xew York, 1871, vol. v., p. 687. 

2 BuDfJE, Lehrbuch der specidhn Physiologic dcs Mcnschcn, Leipzig, 1862, 
S. 510, 767. 

In a recent review of the theory proposed by Cyon ; viz., that the true ^aso- 
motor centres are located in the encephalon, above the medulla oblongata and 



FUNCTIONS OF THE SYMPATHETIC SYSTEM. 439 

centres, sometimes as the result of impressions received 
through the nerves of general sensibility, produces contrac- 
tion of the non-striated muscular fibres of the iris, 1 vasa 
deferentia, etc., including the muscular walls of the blood- 
vessels. The contraction of the muscular walls of the ves- 
sels is tonic ; and when their nerves are divided, relaxation 
takes place, and the vessels are dilated by the pressure of 
blood. By this action, the local circulations are regulated 
in accordance with impressions made on sensory nerves, 
the physiological requirements of certain parts, mental emo- 
tions, etc. Secretion, the peristaltic movements of the ali- 
mentary canal, the movements of the iris, etc., are influenced 
in this way. This action is also illustrated in cases of reflex 
paralysis, in inflammations as the result of " taking cold," 
and in many pathological conditions, of which it is not our 
province to treat. The facts already noted with regard to the 
excito-motor action of the spinal cord in the functions of ani- 
mal life have their analogy in the vaso-motor reflex system. 
When the centres are destroyed, when the sensory nerves 
are paralyzed by anaesthetics, or when the true vaso-motor 
nerves are divided, reflex vaso-motor action is abolished. 

The vaso-motor filaments are not confined to the branches 
of the sympathetic, but they exist as well in the ordinary 
cerebro-spinal nerves. Bernard has demonstrated this fact 
in the most conclusive manner. He divided the fourth, 
fifth, sixth, seventh, and eighth pairs of lumbar nj/ves on 
one side in a dog, at the spinal column, and paralyzed mo- 

the cerebellum, and that no effects upon the blood-vessels following irritation 
of the sensory nerves are observed when the encephalon is extirpated, leaving 
the medulla and cerebellum, or when the sensory nerves are paralyzed by anaes- 
thetics, Heidenhain presents positive results in opposition to the negative obser- 
vations of Cycn, at least as far as the experiments after removal of the superior 
parts of the encephalon are concerned. (HEIDENHAIN, Ueber Cyorfs n.ue Theorle 
raleti Innervation der Gefiissntrven. Archiv fur die gesammte Physiologic, 
Bonn, 1871, Bd. iv., S. 551, et seq.) 

1 We assume that dilatation of the iris is produced by the contraction of 
radiating fibres. Their existence, however, is denied by some anatomists. We 
will discuss this question fully under the head of vision. 



440 NERVOUS SYSTEM. 

tion and sensation in the leg of that side, but the tempera- 
ture of the two sides remained the same. He afterward ex- 
posed and divided the sciatic nerve on that side, and then 
noted a decided increase of temperature. 1 This experiment, 
which is only one of a large number, shows conclusively that 
the ordinary mixed nerves contain vaso-motor fibres, which 
are entirely independent of the nerves of motion and sensa- 
tion, a fact which is admitted by all physiologists, and has 
frequently been illustrated in cases of disease in the human 
subject. 

It only remains to show that the phenomena following 
section of the sympathetic in animals are illustrated in cer- 
tain cases of disease or injury in the human subject. It is 
excessively rare to observe traumatic injury confined to the 
sympathetic in the neck. A single case, however, apparently 
of this kind, has lately been reported by Mitchell. A man 
received a gunshot-wound in the neck. Among the phe- 
nomena observed a few weeks after, were, contraction of 
the pupil on the side of the injury, and, after exercise, flush- 
ing of the face upon that side. There was no difference in 
the temperature upon the two sides, during repose, but no 
thermometric observations were made when half of the face 
was flushed by exercise. 2 Dr. Bartholow has reported sev- 
eral cases of unilateral sweating of the head, two observed 
by himself, in several of which there was probably compres- 
sion of the sympathetic from aneurism. In those cases in 
which the condition of the' eye was observed, the pupil was 
found contracted in some and dilated in others. In none 
of these cases, were there any accurate thermometric obser- 
vations. 3 In a series of observations by "Wagner, upon the 
head of a woman, eighteen minutes after decapitation, pow- 

1 BERNARD, RecJierches experimentales sur les nerfs vasculaires et calorifiques 
iu Tjrand sympathtque. Journal de la physiologic, Paris, 1862, tome v., p. 389. 

8 MITCHELL, Injuries of Nerves, Philadelphia, 1872, p. 318. 

3 BARTHOLOW, Unilateral Sweating of the Head. Quarterly Journal of Psycho- 
logical Medicine, New York, 1869, vol. Hi., p. 134, et seq. 



TROPHIC CENTRES AND XEKVES, SO CALLED. 441 

erful galvanization of the sympathetic produced great en- 
largement of the pupil. 1 In such a case as this, it would not 
be possible to make any observations on the influence of the 
sympathetic upon the temperature. 

Trophic Centres and Nerves, so called. 

We have deferred the consideration of the so-called tro- 
phic nerves until we had treated of the functions of the 
sympathetic system, because the vaso-motor nerves, by their 
influence upon the circulation, are evidently connected with 
the phenomena of nutrition. It is not necessary to dwell 
very minutely upon this point ; but cases of disease, as well 
as experiments upon the inferior animals, show that when a 
muscle is paralyzed, as a result of the abolition of nervous 
influence and consequent disease, it becomes atrophied, its 
fibres lose their characteristic structure, and finally become 
incapable of contracting under any stimulus. As we have 
seen that the cerebro-spinal nerves, in addition to their mo- 
tor and sensory fibres, contain vaso-motor elements, it be- 
comes a question whether the muscles be supplied with 
special nerves, aside from those of motion and sensation 
and the vaso-motor nerves, which preside over their nutri- 
tion. Such could properly be called trophic nerves. Many 
pathologists, relying upon the presence of certain lesions 
of cells in the cord, in connection with cases of progressive 
muscular atrophy, admit the existence of trophic cells and 
nerves. It must be admitted, however, that these views 
rest upon pathological facts alone, and have not been de- 
monstrated by physiological experiments or observations. 

After what we have said, it is evident that proper nutri- 
tion of the muscular system depends upon its exercise and 
the integrity of its motor nerves. In the second place, the 
history of monsters shows that the muscular system may be 

1 WAGNER, Note sur qicelques experiences sur la partie cervicale du nerfsympa- 
ihique chez une femme decapitee. Journal de la physiologic, Paris, 1860, tome Ui., 
p. 175. 



442 NERVOUS SYSTEM. 

developed independently of the cerebro-spinal centres. In 
the admirable work of Brachet, on the ganglionic system, 
numerous cases of anencephalic * monsters are detailed, taken 
from Morgagni, Wepfer, Ruisch, Littre, Lallemand, Boux, 
Fauvel, Mery, Saviard, Bouhaud, Schellhase, Heyshan, 
Bayle, Lordat, Sain t-Hila ire, and others, in which the mus- 
cular system was found more or less perfectly developed. 
In some of these, the foetus was delivered at term and lived 
for several hours. In the case reported by Bayle, the child 
was born with two teeth and lived for seven days. Heyshan 
reported a case that lived for six days. When we consider 
the great number of cases of this kind on record, a few of 
which only are cited by Brachet, it is evident that the cere- 
bro-spinal centres are not absolutely necessary to develop- 
ment in utero. Some of the cases reported presented spas- 
modic movements of certain muscles. 2 

While it is certain that a foetus may become developed 
in iitero, when there is reason to suppose that the cerebro- 
spinal influence is wanting and the chief nervous operations 
are effected through the ganglionic system, direct experi- 
ments upon the sympathetic in animals do not positively 
show any influence upon nutrition, except as this system 
of nerves affects the supply of blood to the parts. When we 
divide a sympathetic nerve, there is an apparent exaggera- 
tion of the nutritive processes in. particular parts, and there 
may be inflammatory phenomena, but atrophy of muscles is 
not observed. Indeed, we only have atrophy of muscles 
following division of cerebro-spinal nerves, or, as recently- 

1 The term anencephalic is here used in the sense in which it was employed 
by Saint-Hilaire, as signifying absence of the encephalon and spinal cord, or 
the entire cerebro-spinal axis. It is sometimes applied to cases of absence of 
the encephalon, which are more commonly called acephalous. 

2 BRACKET, Recherches experimentales sur lesfoncliom du system e nerveux yan- 
glionaire, Bruxelles, 1834, p. 103, et seq. 

At the time the work of Brachet was written, it presented an admirable 
account of the physiology of the sympathetic system ; but it antedates the posi- 
tive facts ascertained by Bernard, Brown-Sequard, and other writers, to whom 
we have made frequent reference. 



TROPHIC CENTRES AND NERVES, SO CALLED. 443 

observed cases of disease have shown, after disorganization 
of cells belonging to what we recognize as motor centres. 
As regards the latter condition, there can be no doubt of 
the fact that progressive muscular atrophy is attended with 
disorganization of certain of the motor cells of the spinal 
cord. 

Without fully discussing this subject, which belongs to 
pathology, the facts may be briefly stated as follows : We 
may have progressive atrophy of certain muscles, which may 
be uncomplicated with paralysis, except in so far as there is 
weakness of these muscles, due to partial and progressive de- 
struction of their contractile elements. The only pathologi- 
cal condition in these cases, aside from the changes in the 
muscular tissue, is destruction of certain cells in the antero- 
latcral portions of the cord, with more or less atrophy of 
the corresponding anterior roots. To one has pretended to 
have demonstrated cells in the cord, presenting anatomical 
peculiarities by which they may be distinguished from the 
ordinary motor or sensory elements, but the fact of the de- 
generation of certain cells, others remaining normal, and 
this fact alone, has led to the distinction, by certain writers, 
of trophic cells ; and, of course, these must be connected 
with the muscles by trophic nerves. 1 

"We shall now study the phenomena of progressive mus- 
cular atrophy from a physiological point of view, and see if 
they afford any positive evidence of the existence of special 

1 Cases of progressive muscular atrophy have recently been studied with 
great minuteness, and connected with lesions of certain cells in the cord, by 
various authors ; among whom may be mentioned, Hayem (Xote sur vn cas 
(tairopliie musculaire progressive avec lesions de la modle. Archives de physiologic, 
Paris, 1869, tome ii., pp. 263, 391); Charcot and Joffroy (Deux can d'atrophie 
muzcidaire progressive avec lesions de la substance prise et dcs faiweaux anfero- 
lateral de la moefle epinere. Ibid., pp. 354, 629, 744) ; and Duchenne and Jof- 
froy (De Vatrophie aigue et chronique des cellules nerveuses de la moelle et du bulbe 
rachidien. Ibid., 1870, tome iii., p. 499). 

For a full account of the disease in question, with its relations to the degen- 
eration of nerve-cells, the reader is referred to HAMMOND, Diseases of the Nerrov* 
System, New York, 1871 p. 663, et *eq. 



4:44 NERVOUS SYSTEM. 

cells and nerves presiding over the nutrition of the muscular 
system, or whether the phenomena observed cannot be ex- 
plained by the partial degeneration of the ordinary motor 
cells and nerves. 

There can be no doubt of the fact that the cells of the 
antero-lateral columns of the spinal cord preside over mo- 
tion, and that the stimulus' generated in these cells is con- 
veyed to the muscles by the anterior roots of the spinal 
nerves. It is a fact, no less definite, that when a muscle or 
a part of a muscle is deprived of the motor stimulus by 
which it is brought into action, its fibres atrophy, become 
altered in structure, and lose their contractility. Starting 
with these two well-defined physiological propositions, and 
assuming that a few of the ordinary motor cells of the cord 
are destroyed we will not call them trophic cells what 
are the phenomena to be expected as a consequence of such 
a lesion ? Reasoning from what we know of the physiology 
of the nervous system, we should expect to find the follow- 
ing conditions : 

The destruction of certain motor nerve-cells would cer- 
tainly produce degeneration of the fibres to which they give 
origin. This has been observed ; for, in this condition, the 
anterior roots arising from the diseased portions of the cord 
are atrophied. This occurs when any motor nerves are 
separated from their cells of origin, and there is no necessity 
of assuming the existence of special trophic cells or nerves. 

If a few of the motor cells be affected with disease, and 
the degeneration be gradual and progressive, we should 
expect progressive and partial paralysis of the muscles to 
which their nerves are distributed. This paralysis, confined 
to a limited number of fibres of particular muscles or sets 
of muscles, would give the idea of progressive weakening 
of the muscles, and the phenomena would not be those 
observed in complete paralysis, produced by section of the 
motor nerves. These are precisely the phenomena observed 
in progressive muscular atrophy, preceding the paralysis, 



TEOPHIC CENTRES AND NERVES, SO CALLED. 445 

which is the final result of the disease, and these do not 
involve the action of any special centres or nerves. 

As regards the muscular atrophy itself, if the nervous 
stimulus be progressively destroyed, the muscular tissue will 
necessarily undergo degeneration and atrophy. 

AVith the above considerations, we leave the trophic cells 
and nerves to the pathologist, and can only admit the exist- 
ence of centres and nerves specially and directly influencing 
the nutrition of the muscular system, when it has been de- 
monstrated that there are lesions of particular structures in 
the nervous system, which produce phenomena that cannot 
be explained by our knowledge of the action of ordinary 
motor and sensory nerves and of the vaso-motor system. 1 

AVe have thus endeavored to represent what is actually 
known concerning the sympathetic system, but it is evident 
that we have much to learn with regard to its physiology. 
The great sympathetic ganglia may have functions of which 
we have no definite idea; and we are better prepared to 
advance our knowledge in this direction, by admitting our 
ignorance, than by attempting to supply the deficiencies hi 
our positive information by theories unsupported by facts. 

1 \Ve have discussed the question of the existence of trophic nerves from a 
physiological point of view only. In a late review of the subject, by Dr. Hand- 
field Jones, the same opinion is expressed, based upon pathological arguments, 
as will be seen by the following quotation : 

" In conclusion, I may state that my review of the subject leads me to dis- 
credit very much the doctrine that there exists a special class of trophic nerves ; 
inasmuch as all the phenomena, to explain which their existence might be in- 
voked, seem to be fairly explicable by alterations in the condition of those 
which have been long familiar to us." (HASDFIELD JONES, Are there Special 
Trophi-: Xen-es? St. George's Hospital. Reports, London, 1868, vol. iii., p. 109.) 



CHAPTER XYI. 



SLEEP. 

General considerations Condition of the organism during sleep Dreams Re- 
flex mental phenomena during sleep Condition of the brain and nervous 
system during sleep Theories of sleep Anaesthesia and sleep produced 
by pressure upon the carotid arteries Differences between natural sleep, 
and stupor and coma Regeneration of the brain-substance during sleep 
Theory that sleep is due to a want of oxygen Condition of the various func- 
tions of the organism during sleep. 



we remember that about one-third of our existence 
is passed in sleep, and thai, at this time, voluntary motion, 
sensation, the special senses, and various of the functions of 
the organism, are greatly modified, the importance of a physi- 
ological study of this condition is sufficiently apparent. The 
subject of sleep is most appropriately considered in connec- 
tion with the nervous system, for the reason that the most 
important modifications in function are observed in the 
cerebro-spinal axis and nerves. Hepose is as necessary to 
the nutrition of the muscular system as proper exercise ; but 
repose of the muscles relieves the fatigue due to exercise, 
without sleep. It is true that after violent and prolonged 
exertion, there is frequently a desire for sleep, but simple 
repose will often restore the muscular power. After the 
most violent effort, a renewal of muscular vigor is most easily 
and completely effecte'd by rest without sleep, a fact familiar 
to all who are accustomed to athletic exercises. The glands 
engaged in the production of the true secretions need certain 
Intervals of repose ; but this does not necessarily involve 



SLEEP. 447 

fileep. After prolonged and severe mental exertion, how- 
ever, or after long-continued muscular effort which involves 
an excessive expenditure of the so-called nerve-force, sleep 
becomes an imperative necessity. If the nervous system be 
not abnormally excited by effort, sleep follows moderate 
exertion as a natural consequence, and is the only physi- 
ological means of complete restoration ; but the two most 
important muscular acts ; viz., those concerned in circulation 
and respiration, are never completely arrested, sleeping or 
waking, though they undergo certain modifications. 

In infancy and youth, when the organism is in process 
of development, sleep is more necessary than in adult life or 
old age. The infant does little but sleep, eat, and digest. 
In adult life, under perfectly physiological conditions, we 
require about eight hours of sleep ; some persons need less, 
but very few require more. In old age, unless after extraor- 
dinary exertion, less sleep is required than in adult life. 
Each individual learns by experience how much sleep is 
necessary for perfect health, and there is nothing which more 
completely incapacitates one for mental or muscular effort, 
especially the former, than loss of rest. 

Sleeplessness is one of the most important of the predis- 
posing causes of certain forms of brain-disease, a fact which 
is well recognized by practical physicians. One of the most 
refined and exquisite methods of torture is long-continued 
deprivation of sleep ; and persons have been known to sleep 
when subjected to acutely painful impressions. Severe mus- 
cular effort, even, may be continued during sleep. In forced 
marches, regiments have been known to sleep while walking ; 
men have slept soundly in the saddle ; persons will some- 
times sleep during the din of battle ; and other instances 
illustrating the imperative demand for sleep after prolonged 
vigilance might be cited. 1 It is remarkable, also, how noises 

1 For a number of curious and interesting examples of sleep under the most 
unfavorable circumstances, the reader is referred to the admirable work of Dr 
Hammond (Sleep and its Derangements, Philadelphia, 1869, p. 14, et seq.). 

129 



448 NERVOUS SYSTEM. 

to which we have become accustomed will fail to disturb our 
natural rest. Those who have been long habituated to the 
endless noise of a crowded city frequently find difficulty in 
sleeping in the oppressive stillness of the country. "We must 
have sleep ; and this demand is so imperious, that we soon 
accommodate ourselves to the most unfavorable surrounding 
conditions. It is remarkable, also, that prolonged exposure 
to intense cold induces excessive somnolence, and if this be 
not resisted, the sleep passes into stupor, the power of resist- 
ance to cold becomes rapidly diminished, and death is the 
inevitable result. Intense heat often produces drowsiness, 
but, as is w T ell known, is not favorable to natural sleep. We 
generally sleep less in summer than in winter, though in 
summer, perhaps, we are less capable of protracted mental 
and physical exertion. 

Sleep is preceded by an indescribable feeling of drowsi- 
ness, an indisposition to mental or^physical exertion, and a 
general relaxation of the muscular system. It then requires 
a decided eifort to keep awake ; and if we yield to the sopo- 
rific tendency, the voluntary muscles cease to act, the lids 
are closed, we cease to appreciate the ordinary impressions 
of sound, and we sometimes pass into a dreamless condition, 
in which we lose all knowledge of existence. We say some- 
times, because the mind is not generally inactive during 
what we may regard as normal sleep. We may have dreams 
which are not due, as far as can be ascertained, to impres- 
sions from the external world received during sleep. Ideas 
in the form of dreams may be generated in the brain from 
impressions previously received while awake, or trains of 
thought may be gradually extended from the moments im- 
mediately preceding sleep into the insensible condition. 
During the nine years that we have been almost unremit- 
tingly engaged in the preparation of this work, we have 
frequently labored during sleep for an entire night to no 
purpose, it is true upon difficult questions to which we had 
devoted a great deal of thought. 



DREAMS. 449 

There may be, during sleep, mental operations of which 
we have no consciousness or recollection, unconscious cere- 
bration, as it is called by Carpenter. 1 It is well known that 
we vividly remember dreams immediately on awakening, 
but that the recollection of them rapidly fades away, unless 
they be brought to mind by an effort to remember and re- 
late them. Whatever be the condition of the mind in sleep, 
it* the sleep be normal, there is a condition of repose of the 
cerebro-spinal system and an absence of voluntary effort, 
which restore the capacity for mental and physical exertion. 

The impressionability and the activity of the human mind 
are so great, most of the animal functions are so subordinate 
to its influence, and we are so subject to unusual mental con- 
ditions, that it is difficult to determine with exactness the 
phenomena of sleep that are absolutely physiological, and to 
separate those that are slightly abnormal. We cannot assert, 
for example, that a dreamless sleep, in which our existence 
is, as it were, a blank, is the only normal condition of repose 
of the system ; nor can we determine what dreams are due 
to previous trains of thought, to impressions from the exter- 
nal world received during sleep, and are purely physiologi- 
cal, and what are due to abnormal nervous influence, disor- 
dered digestion, etc. We may assume that an entirely re- 
freshing sleep is normal, and that is all. 

That reflex ideas originate during sleep, as the result of 
external impressions, there can be no doubt ; and we have 
already alluded to this point under the head of reflex action. 2 
The most remarkable experiments upon the production of 
dreams of a definite character, by subjecting a person during 
sleep to peculiar influences, are those of Maury. The hallu- 
cinations produced in this way are called hypnagogic, 3 and 

1 CARPENTER, Principles of Human Physiology, Philadelphia, 1853, p. 784. 

2 See page 300 

3 From its derivation, this term is .properly applied only to phenomena ob- 
served at the instant when we fall asleep, or when we are imperfectly awakened, 
and not to the period of most perfect repose. 



450 NERVOUS SYSTEM. 

they occur when the subject is not in a condition favorable 
to sound sleep. The experiments made by Maury upon him- 
self are so curious and interesting, that we quote the most 
striking of them in full : 1 

FIRST OBSERVATION. " I was tickled with a feather succes- 
sively on the lips and inside of the nostrils. I dreamed that 
I was subjected to a horrible punishment, that a mask of 
pitch was applied to my face, and then roughly torn off, 
tearing the skin of the lips, the nose, and the face. 

SECOND .OBSERVATION. "A pair of pincers is held at a 
little distance from my ear, and rubbed with a steel scissors. 
I dreamed that I heard the ringing of bells ; this soon be- 
came the tocsin, and I imagined myself in the days of June, 
1848. 

THIRD OBSERVATION. " I was caused to inhale Cologne- 
water. I dream that I am in a perfumer's shop, and the 
idea of perfumes doubtless awakens the idea of the East : 'I 
am in Cairo, in the shop of Jean Marie Farina. Many ex- 
travagant adventures follow, the connection of which es- 
capes me. 

FOURTH OBSERVATION. " I am caused to smell a burning 
match. I dream that I am at sea (remark that the wind 
was then blowing in through the windows), and that the 
Saint-Barbe blew up. 

FIFTH OBSERVATION. " I am slightly pinched on the 
nape of the neck. I dream that a blister is applied, which 
recalls the recollection of a physician who had treated me 
in my infancy. 

SIXTH OBSERVATION. "A piece of hot iron is held to 
my face, keeping it far enough removed, so that the sensa- 
tion of heat should be slight. I dream of chauffeurs, who 
enter houses and force the inmates, by putting their feet 
to the fire, to reveal where their money was. The idea of 
the chauffeurs immediately suggests that of the Duchess 
d'Abrantes, who, I suppose in my dream, has taken me as 

1 MAURY, Le sommeil el les reves, Paris, 1865, p. 132, ef seq. 



' DEEAMS. 4:51 

secretary. I had, indeed, long ago read in the memoirs 
of this intelligent woman certain details concerning the 
chauffeurs. 

SEVENTH OBSERVATION. "The word parafagaramus is 
pronounced in my ear. I hear nothing, and awake, hav- 
ing had rather a vague dream. The experiment is repeat- 
ed when I am asleep in my bed, and the word maman is 
pronounced many times in succession. I dream of different 
things, but in this dream I heard the humming of bees. 
The same experiment, repeated several days after, when I 
was scarcely asleep, was more conclusive. The words Azor, 
Castor ', Leonore, were pronounced in my ear ; on awaking, 
I recollected that I had heard the last two words, which I 
attributed to one of the persons who had conversed with 
me in my dream. 

" Another experiment of the same kind likewise showed 
that the sound of the word, and not the idea attached to it, 
had been perceived. The words chandeUe, haridelle, were 
pronounced in my ear, many times in succession. I awoke 
suddenly of my own accord, saying, (?est die. It was im- 
possible for me to recall what idea I attached to this answer. 

EIGHTH OBSERVATION. " A drop of water is allowed to 
fall on my forehead, I dream that I am in Italy, that I am 
very warm, and that I am drinking the wine of Orviette. 

XIXTH OBSERVATION. " A light, surrounded with a red 
paper, is many times in succession passed before my eyes. 
I dream of a tempest of lightning, and all the remembrance 
of a violent storm which I had encountered in the English 
Channel, in going from Morlaix to Havre, is present in my 
mind." 

As regards dreams due to external impressions, it is a 
curious fact, which has been noted by many observers, and 
one which accords with the personal experience of all who 
have reflected upon the subject, that trains of thought and 
imaginary events, which seerA to pass over a long period of 
time in our dreams, actually occur in the brain within a 



452 NERVOUS SYSTEM. 

few seconds. A peison is awakened by a certain impres- 
sion, which undoubtedly gives rise to a dream that seems 
to occupy hours or days, and yet the period of time between 
the impression and the awakening is hardly more than a few 
seconds ; and persons will drop asleep for a very few min- 
utes, and yet have dreams, with the most elaborate details, 
and apparently of great length. It is unnecessary to cite 
the numerous accounts of literary compositions of merit, the 
working out of difficult mathematical problems in dreams, 
etc., some of which are undoubtedly accurate. If it be true, 
that the mind is capable of forming consecutive ideas during 
sleep, which can hardly be doubted, there is no good reason 
why these phenomena should not occur, and the thoughts 
should not be remembered and noted, immediately on awak- 
ening. In most dreams, however, the mind is hardly in a 
normal condition, and the brain generally loses the power 
of concentration and of accurate reasoning. We sometimes 
commit atrocious crimes in our dreams, without appreciating 
their enormity, and are often placed in the most absurd 
and impossible conditions, without any idea, at the time, of 
their extraordinary and unnatural character. This is a fact 
sufficiently familiar to every one, and is one which does not 
admit of satisfactory explanation. 

We have made no attempt to offer an explanation of the 
curious psychological phenomena presented during sleep, 
and, indeed, we know little enough of the action of the 
mind at any time ; but we have merely given the above as 
examples of what we may call reflex mental phenomena. 
Somnambulism, general ansesthesia, sleep from hypnotics, 
the so-called magnetic sleep, ecstasy, catalepsy, trance, etc., 
are abnormal conditions, which we will only consider in so 
far as they resemble natural sleep. 

Condition of the Brain and Nervous System during Sleep. 

As we have already seen, during sleep, the brain may be 
in a condition of absolute repose, at least, as far as we have 



THEORIES OF SLEEP. 453 

any subjective knowledge of mental operations, or we may 
have more or less connected trains of thought. There is, 
also, as a rule, absence of voluntary effort, though move- 
ments may be made, to relieve discomfort from position or 
external irritation, without awakening. The sensory nerves 
retain their properties, though the general sensibility is some- 
what blunted ; and the same may be said of the special senses 
of hearing, smell, and probably of taste. The peculiar dreams, 
induced in the case of Maury by red lights, show that the 
sense of sight is not entirely lost. There is every reason to be- 
lieve, however, that the functions of the sympathetic system 
are not disturbed or affected by sleep, if we except the action 
of the vaso-motor nerves upon the circulation in the brain. 

Two opposite theories have long been in vogue with re- 
gard to the immediate cause of sleep. In one, this condition 
is attributed to venous congestion and increased pressure of 
blood in the brain, and this view probably had its origin in 
the fact that cerebral congestion induces stupor or coma. 
Stupor and coma, however, are entirely distinct from natu- 
ral sleep ; for here, the functions of the brain are suspend- 
ed, there is no consciousness, no dreaming, and the con- 
dition is manifestly abnormal. In animals rendered coma- 
tose by opium, the brain may be exposed and is found 
deeply congested with venous blood. The same condition 
often obtains in profound anaesthesia from chloroform, but a 
state of the brain very nearly resembling normal sleep is 
observed in anaesthesia from ether. These facts have been 
positively demonstrated by experiments upon living ani- 
mals, and have been observed in the human subject, in 
cases of injury of the head. When opium is administered 
in large doses, the brain is congested during the condition 
of stupor or coma, but this congestion is relieved when the 
animal passes, as sometimes happens, from the effects of the 
agent into a natural sleep. 1 In view of these facts, and 
others which will be stated hereafter, it is unnecessary to 

1 HAMMOND, Sleep and its Derangements,, Philadelphia, 1869, pp. 26, 32. 



4:54 NERVOUS SYSTEM. 

discuss the theory that sleep is attended with, or is produced 
by, congestion of the cerebral vessels. 

The idea that the circulation in the brain is diminished 
during sleep has long been entertained by cartain physiolo- 
gists ; but until within a few years, it has rested chiefly upon 
theoretical considerations. We find this view enunciated by 
Blumenbach, in the following words : " These remote causes 
may induce the proximate cause, which, upon mature con- 
sideration, I think probably consists in a diminished or im- 
peded flow of oxygenated (arterial) blood to the brain, for 
that fluid is of the highest importance, during the waking 
state, to the reaction of the sensorium upon the senses and 
voluntary motions." This opinion was not entirely theo- 
retical, as is seen by the following statement: "Besides 
other phenomena which accord with this explanation, one is 
very remarkable which I witnessed in a living person, and 
has been already noticed that of the brain sinking when- 
ever he was asleep, and swelling again with blood the mo- 
ment he awoke." 1 

Passing over arguments by the older writers, for and 
against this theory of sleep, we come to the researches of 
Durham, in 1860, in which it w r as clearly demonstrated that 
the supply of blood to the brain is always greatly diminished 
during sleep. These experiments w^ere made upon dogs. 
A piece of the skull, about the size of a shilling, was removed 
with a trephine, and a w r atch-glass was accurately fitted to 
the opening and cemented at the edges with Canada balsam. 
"When the animals operated upon in this way were awake, 
the vessels of the pia mater were seen moderately distended, 
and the circulation was active ; but during perfectly natural 
sleep, the brain retracted and became pale. " The contrast 
between the appearances of the brain during its period of 
functional activity, and during its state of repose or sleep was 
most remarkable." 2 These observations were confirmed in 

1 BLUMENBACH, The Institutions of Physiology, Philadelphia, 1817, pp. 178, 179. 

2 DURHAM, The Physiology of Sleep. Guy's Hospital Report^ Third Series, 
London, 1860, voL vi., p. 153, et seq. 



THEORIES OF SLEEP. 455 

the most satisfactory manner by Prof. Hammond, who, in 
1854, noted the changes in the circulation during sleep in a 
man who had a large opening in The skull from a railroad- 
accident. These observations were made independently of 
those of Durham, but were not published until some time 
after. 1 Prof. Hammond cites numerous observations illus- 
trating the diminished circulation in the brain during sleep, 
in the human subject, which it is unnecessary to refer to in 
detail, and this fact may now be considered as definitively 
settled. 3 He also devised an instrument for measuring the 
extent of the cerebral pressure. This instrument consists of 
a brass tube, which is screwed into an opening made in the 
skull, and is connected with a small glass tube filled with 
colored water. The lower end of the brass tube is covered 
with a thin sheet of rubber, which rests on the brain, the 
cerebral pressure being marked by the height of the liquid 
in the glass tube. In experiments made with this apparatus, 
Prof. Hammond fully confirmed the results of his previous 
observations. 8 

The influence of diminished supply of blood to the brain 
has been illustrated by compression of both carotid arteries. 
In an experiment performed on his own person, Dr. Fleming 
produced immediate and profound sleep in this way, and 
this result invariably .followed in subsequent trials upon 
himself and others. 4 We have already alluded to the obser- 
vations of "Waller, who produced anaesthesia in patients by 
pressure upon both pneumogastric nerves ; but, as we then 
remarked, the nerves are so near the carotid arteries that 
they could hardly be compressed, in the human subject, 

1 HAMMOND, Sleep audits Derangements, Philadelphia, 1869, p. 37, et seq. 

' 2 An interesting case of exposure of the brain in the human subject i& re- 
ported by Dr. Brown (American Journal of the Medical Sciences, New Series, 
Philadelphia, 1860, vol. si., p. 400). 

3 HAMMOND, op. cit., Appendix. 

4 FLEMING, Note on the Induction of Sleep and Anaesthesia by Compression of 
the Carotids. British and Foreign Medico-Chirurgical Review, London, 1855, voL 
XV., p. 529. 



4:56 NEKVOUS SYSTEM. 

without interfering with the current of blood, and such 
experiments do not positively show whether the loss of sen- 
sibility be due to pressure upon the nerves or upon the ves- 
sels. 1 An important observation bearing upon this point is 
the following, cited by Prof. Hammond : In a lady affected 
with cirsoid aneurism of the scalp, both carotids were tied 
at different times, one by the late Dr. J. Kearney Rogers, 
and the other by Prof. "W. II. Yan Buren. " No peculiar 
symptoms were observed in consequence of these operations, 
except the supervention of persistent drowsiness, which was 
especially well marked after the last operation, and which, 
even now, is at times quite troublesome." The last opera- 
tion was performed seven years ago. a The bearing of these 
facts is sufficiently evident. They all go to show that the 
supply of blood to the brain is very much diminished during 
natural sleep, and that sleep may be induced by retarding 
the cerebral circulation by compressing the vessels of supply. 
When the circulation is interfered with by compressing the 
veins, congestion is the result, and we have stupor or coma. 
If diminished now of blood through the cerebral vessels 
be the cause of natural sleep, it becomes important to inquire 
how this condition of physiological anaemia is brought about. 
It must be, that when the system requires sleep, the vessels 
of the brain contract in obedience to a stimulus received 
through the sympathetic system of nerves, diminishing the 

1 See page 256. 

2 HAMMOND, op. cit., p. 42. 

Ligation of both carotids, when the patient recovers from the operation, does 
not always induce drowsiness, which is probably due to free collateral circulation, 
by which, in some cases, the full supply of blood to the brain" is maintained. 
In a remarkable case published by Mussey, both carotids were tied for aneu- 
rism, one being operated upon about six weeks after the other. In this case, it 
is remarked that " at no period subsequently to the operation of tying the 
second carotid, with the exception of the faintness and debility which occurred 
from the actual loss of blood on the removal of the tumor, has there been a 
single symptom of deficiency of blood in the brain." (MUSSET, Case of Aneu- 
nsm by Anastomosis, in which both the Primitive Carotid Arteries were tied. 
American Journal of the Medical Sciences, Philadelphia, 1829, vol. v., p. 316.) 



THEO&IES OF SLEEP. 457 

supply of blood, here, as in other parts, under varied physio- 
logical conditions. The vessels of the brain are provided 
with vaso-motor nerves, and it is sufficient to have noted 
that the arteries are contracted during sleep, the mechanism 
of this action being well established by observations upon 
other parts of the circulatory system. Contraction of the 
vessels of the pia mater has been observed by Kathnagel 
and others, though there is some discussion with regard to 
its exciting cause. 1 

It must be acknowledged that we know but little of the 
intimate nature of the processes of nutrition of the brain 
during its functional activity and in repose ; but there can 
be no doubt of the fact that there is more or less cerebral 
action at all times when we are awake. Though the mental 
processes are much less active during sleep, even at this time, 
the operations of the brain are not always suspended. It is 
equally well established, that exercise of the brain is attended 
with physiological waste of nervous substance, and, like other 
parts of the organism, its tissue requires periodic repose to 
allow of the regeneration of the substance consumed. Analo- 
gies to this are to be found in parts that are more easily 
subjected to direct observation. The muscles require repose 
after exertion, and the glands, when not actively engaged in 
discharging their secretions, present intervals of rest. 3 As 
regards the glands, during the intervals of repose, the supply 
of blood to their tissue is very much diminished. It is prob- 
able, also, that the muscles in action receive more blood than 
during rest ; but it is mainly when these parts are not active, 
and when the supply of blood is smallest, that the processes 
of regeneration of tissue seem to be most efficient. As a 
rule, the functional activity of parts, while it is attended 

1 A. reference to these experiments is to be found in the Journal of Anatomy 
and Physiology, Cambridge and London, 1871, vol. v., p. 401. 

2 Luys has compared the condition of repose of the brain, with its diminished 
supply of blood, to the period of inactivity of the glands (Recherches sur k 
systhae nerveux, Paris, 1865, p. 450). 



458 NERVOUS SYSTEM. 

with an increased supply of blood, is a condition more or 
less opposed to the process of repair, the hypersemia being, 
apparently, a necessity for the marked and powerful mani- 
festations of their peculiar functions. When the parts are 
in active function, the blood seems to be required to keep at 
the proper standard the so-called irritability of the tissues, 
and to increase their power of action under proper stimulus. 
Exercise increases the power of regeneration and favors full 
development, in the repose which 'follows ; but during 
rest, the tissues have time to appropriate new matter, and 
this does not seem to involve a large supply of blood. A 
muscle is exhausted by prolonged exertion ; and the large 
quantity of blood passing through it carries away carbonic 
^acid, urea, and other products of disassimilation, which are 
all increased in amount, until it gradually iises up its capa- 
city for work. Then follows repose ; the supply of blood is 
reduced, but, under normal conditions, the tissue repairs the 
waste which has been excited by action ; the blood furnishing 
nutritive matter and carrying away a comparatively small 
amount of effete products. 

We may safely assume that processes analogous to those 
just described take place in the brain. By absence of vol- 
untary effort, we allow the muscles time for rest and for the 
repair of physiological waste, and their active function is for 
the time suspended. As the activity of the brain involves 
consciousness, volition, the generation of thought, and, in 
short, the mental condition observed while awake, complete 
repose of the brain is characterized by the opposite condi- 
tions. It is true that we rest the brain without sleep, by 
abstaining from mental effort, by the gratification of certain 
of the senses, and by mental distraction of various kinds, 
and that the mind may work to some degree during sleep ; 
but during the period of complete repose, that condition 
which is so necessary to perfect health and full mental vigor, 
we lose consciousness, volition, there is no thought, and the 
brain, which does not receive blood enough to stimulate it 



THEORIES OF SLEEP. 4:59 

to action, is simply occupied in the insensible repair of its 
substance and is preparing itself for future work. The ex- 
haustion of the muscles producas a sense of fatigue of the 
muscular system, indisposition to muscular exertion, and a 
desire for rest, not necessarily involving drowsiness ; fatigue 
of the brain is manifested by indisposition to mental exer- 
tion, dulncss of the special senses, and a desire for sleep. 
Simple repose will relieve physiological fatigue of muscles ; 
and, when a particular set of muscles has been used, the 
fatigue disappears when these muscles alone are at rest, 
though others be brought into action. Sleep, and sleep 
alone, relieves fatigue of the brain. "Wlien the sleep has 
continued long enough for the rest of the brain and the re- 
pair of its tissue, we awake, prepared for new effort. 

AVe have now only to refer to a new theory of sleep, 
proposed by Sommer. Taking as a basis the researches of 
Pettenkofer and Yoit on respiration, Sommer advances the 
idea that, when the brain is active, or while we are awake, 
the system appropriates but a small quantity of oxygen in 
respiration, and eliminates a relatively large proportion of 
carbonic acid ; after a time, the oxygen thus appropriated is 
consumed, and the system demands a new supply ; during 
sleep, the organism appropriates oxygen largely, and elimi- 
nates a relatively small amount of carbonic acid. When 
the elimination of carbonic acid at the expense of the oxy- 
gen stored up reaches a certain point, the necessity for a 
farther supply of oxygen induces sleep ; and when, during 
sleep, oxygen has been appropriated in sufficient quantity, 
the system awakes, prepared for a new period of activity of 
the animal functions. 1 

By reference to the researches of Pettenkofer and Yoit, 
we find that these observers, in experiments on a man con- 
fined in a chamber in which the interchanges of gases in 
respiration could be estimated, noted, in twenty-four hours, 

1 SOMMER, Xeue Theorie des Schlafes.Zeitschrift fur rationeHe Median, 
Dritte Reiho, Leipzig uiid Heidelberg, 1868, Bd. xxxiii., S. 214, et seq. 



460 NERVOUS SYSTEM. 

that the subject of the observation, awake, but in a condition 
of complete repose, appropriated sixty-seven per cent, of 
the entire amount of oxygen of the twenty-four hours dur- 
ing the night, and thirty-three per cent, during the day, 
while he eliminated fifty-eight per cent, of the entire amount 
of carbonic acid excreted, during the day, and forty-two per 
cent, during the night. When the subject of the experi- 
ment worked during the day, by turning a heavy wheel, 
the appropriation of oxygen was thirty-one per cent, for the 
day, and sixty-nine per cent, for the night ; the elimination 
of carbonic acid was sixty-nine per cent, for the day, and 
thirty-one per cent, for the night. According to these ob- 
servations, the system stores up oxygen at night for use 
during the day, at this time eliminating a relatively small 
quantity of carbonic acid ; and, during the day, excretes 
more carbonic acid than during sleep, appropriating then a 
relatively small amount of oxygen. 1 

This theory of sleep seems to rest upon observations too 
restricted to be adopted without reserve. It is stated, in- 
deed, that the first experiments of Pettenkofer and Yoit 
were not confirmed in other observations made upon the 
same person. a It is hardly possible, with our present infor- 

1 PETTENKOFER UNO VOIT, Ueber Kohlensdureausscheidung und Sauerstoff- 
aufnahme wahrend des Wachens und Schlafens beim Menschen. Annalen der 
Chemie und Pharmacie, Leipzig und Heidelberg, 186*7, Bd. cxli., S. 300, 303. 

2 Journal of Anatomy and Physiology, Cambridge and London, 1868, vol. ii., 
p. 181. 

The statement alluded to above is to be found in the report on physiology, 
by Drs. Rutherford, Gamgee, and Frazer (loc. cit.\ but there is no indication 
where the new observations of Pettenkofer and Voit were published. We find 
no allusion to any experiments later than those published in 1867 in the Anna- 
len dcr Chemie und Pharmacie, in Schmidts Jahrbiicher, from that date to the 
present time. In an article by these authors on the excretions, etc., observed 
in a patient affected with leucocythemia, it appears that the smallest difference 
in the appropriation of oxygen during the day and at night, in a heakhy person, 
was fifty-one per cent, for the day, and forty-nine per cent, at night, which is 
so slight a variation, that it may practically be disregarded. (PETTENKOFER UND 
VOIT, Ueber den Stojfverbrauch bei einem leukdmischsn Manne. Zeitschrift fur 
Biologic, Munchen, 1869, Bd. v., S. 327.) 



THEORIES OF SLEEP. 461 

mation, to assume that sleep is due simply to want of oxy- 
gen, and it is more in accordance with well-established 
physiological facts to attribute it to a necessity for the gen- 
eral regeneration of the nervous tissue, though into this, 
the necessity for oxygen may enter as one element in the 
physiological repair. 

During sleep, nearly all of the functions, except those 
directly under the control of the sympathetic nervous sys- 
tem, are diminished in activity. The circulation is slower, 
and the pulsations of the heart are less frequent, as well as 
the respiratory movements. These points have already been 
considered under the heads of circulation and respiration. 
AVe have but little positive information with regard to the 
relative activity of the processes of digestion, absorption, 
and secretion, during sleep. The drowsiness which many 
persons experience after a full meal is probably due to a de- 
termination of blood to the alimentary canal, and a conse- 
quent diminution in the supply to the brain. 



INDEX. 



Abercrombie, brain of, 348 

Agraphia, 358 

Alternate paralysis, 147, 401 

Amputated members, sensation in, 89 

Amylacea, corpora, 59 

Andral's ninety-three cases of dis- 
ease of the cerebellum, analysis 

of, 373 

Anelectrotonus, 119 

Anencephalic and acephalic foe- 
tuses, 442 

Aphasia, 350 

first case of, on record, 352 

cases of, 354 

Arachnoid, 259 

Arnold's ganglion, 420 

Associated movements, 86 

Atrophy, progressive muscular, . . 443 
Auricular branches of the pneumo- 

gastrics (see pneumogastric), . . 216 
Axis-cylinder (see nerve-fibre), ... 21 

Bcsoin de respirer, 236, 408 

Brain (see cerebrum and encepha- 
lon), 313 

Carotids, tendency to sleep, pro- 
duced by compression or ligature 

of, 455,456 

Catelectrotonus, 119 

Cauda equina, 265 

Cephalo-rachidian fluid, 261 

effects of sudden discharge 

or increase of, 263 

properties, composition, and 

functions of, 264 

Cerebellum, physiological anatomy 

of, 359 

course of the fibres in, 361 

130 



Cerebellum, general properties of, 362 

functions of, 363 

extirpation of, in animals, ... 365 

pathological facts bearing up- 
on the functions of, 372 

analysis of Andral's ninety- 
three cases of disease of, 373 

additional cases of disease of, 

in the human subject, 378-386 

conclusions with regard to the 

functions of, in muscular coor- 
dination, 386 

connection of, with the gen- 
erative functions, 388 

movements of the testicles, 

vasa deferentia, uterus, Fallo- 
pian tubes, etc., produced by 

irritation of, 363, 389 

comparative size of, in stal- 
lions, mares, and geldings, 389 

development of, hi the lower 

animals, 390 

paralysis from disease or in- 
jury of, 390 

properties of the peduncles 

of, , 415 

Cerebrate of soda, 59 

Cerebration, unconscious, 449 

Cerebric acid, 59 

Cerebrine, 59 

Cerebro-spinal axis, general ar- 
rangement of, 257 

membranes of, 258 

Cerebro-spiual fluid (see cephalo- 

rachidian fluid), 261 

Cerebrum, supposed regeneration 

of, after extirpation, 63, 336 

reflex action of, in dreams, 

800,449 



464: 



INDEX. 



Cerebrum, physiological anatomy 

of (see encephalon), 321 

general properties of, 322 

excitability of certain por- 
tions of, 323 

functions of, 324 

extirpation of, in animals,. . . 327 

pathological facts bearing up- 
on the functions of, 337 

effects of haemorrhage in,. . . 337 

development of, in idiots, . . . 338 

comparative development of, 

in the lower animals, 340 

development of, in different 

races of men, and in different in- 
dividuals, 341 

comparison of the quality of, 

with the quality of muscle, 342 

table of weights of the brain 

in the Caucasian, negro, etc.,. . . 345 

table of weights of the brain 

in individuals, 345 

location of the faculty of ar- 
ticulate language in the anterior 

lobes of,. . 350 

contraction of vessels of, dur- 
ing sleep, 457 

physiological repair of, dur- 
ing sleep, 458 j 

Cervical ganglia of the sympa- 
thetic, 421 

Cholesterine, 50 

Chorda tympani, functions of,. . . 155 
influence of, upon the sub- 
maxillary secretion, 158 

Choroid plexus, 260 

Ciliary ganglion, 419 

Ciliary nerves, influence of, upon 

the iris, 133,419 

Cilio-spinal centre, 438 

Circulation, influence of the pneu- 

' mogastrics upon, 223 

influence of the sympathetic 

system upon 42, 433 

Coordination of muscular actions, 
probable function of the poste- 
rior white columns of the spinal 

cord in, 289 

effects upon, of injury or re- 
moval of the cerebellum, 365 

connection of the cerebellum 

with...... 386 

Cornea, termination of nerves in, 45 

Corpora amylacea, 59 

Corpora striata, functions of, 393 



Corpus callosum, 412 

Corpus striatum, effects of lesion 

of, 337 

Cuvier, brain of, 347 

Cyou, depressor-nerve of,... 208, 229 

Death, definition of, *. 410 

Deglutition, influence of the facial 
nerves upon, ' f 162 

- influence of the spinal acces- 
sory nerves upon, 175 

influence of the sublingual 

nerves upon, 182 

influence of the superior 

laryngeal nerves upon, 218 

influence of the oesophageal 

branches of the pneumogastrics 
upon, 241 

Depressor-nerve of the circula- 
tion, 208, 229 

Diarrhoni, ^influence of the sympa- 
thetic system in the production 
of,.. 434 

Digestion, influence of the pneumo- 
gastrics upon, 248 

Dreams, reflex action of the cere- 
brum in, 300, 449 

Dupuytren, brain of, 349 

Dura muter, 258 

Ear, effects of paralysis of the fa- 
cial nerve upon, 155 

influence of injury or disease 

of the semicircular canals upon 
the muscular movements (Me- 
niere's disease),. . . . 369 (note), 387 
Electricity, excitation of nerves 

by, 93, 105 

action of, upon the nerves, . . 105 

action of direct, or descend- 
ing, and of inverse, or ascending 

currents, upon the nerves, 106 

derived currents, 112 

induced muscular contrac- 
tion, 112 

current of, from the exterior 

to the cut surface of a nerve,. . 113 

effects of a constant current , 

upon the nervous irritability, . . 114 

Electrotonus, 115 

Encephalon, general arrangement 

of, 313 

different ganglia of, 314 

weight of, 815 

physiological anatomy of, ... 31" 



INDEX. 



465 



Encephalon, ganglia at the base of, 393 
Excito-motor action (see reflex ac- 
tion), 300 

Expression, nerve of (see facial 

nerve), 145 

influence of the facial nerve 

' upon, 165 

Eye, effects of division of the fifth 
nerve upon, 198 

Facial nerve, 145 

physiological anatomy of,. . . 145 

effects upon the eye, of sec- 
tion of fibres of, in the median 
line, in the floor of the fourth 

ventricle, 147 

branches of, 148 

summary of anastomoses and 

distribution of, 151 

properties and functions of, 154 

effects of paralysis of, upon 

the ear, 155 

functions of the chorda tym- 

pani, 155 

influence of, upon gustation, 156 

typical case of division of, in 

the human subject, 157 

influence of, upon the sub- 
maxillary secretion, 158 

influence of, upon the move- 
ments of the palate and uvula, . . 159 
functions of the external 

branches of, 162 

Facial angle 344 (note) 

Fallopian tubes, movements of, 

from irritation of cerebellum, . . 363 
Falx cerebri and falx cerebelli, . . . 259 
Fifth nerve, small root of (nerve 

of mastication), 139, 140 

physiological anatomy of, ... 140 

properties and functions of, . 143 

large root of (see trifacial), . 184 

Filum terminate of the spinal cord, 265 

Fisk, James, Jr., brain of, 348 

Fourth ventricle, 360, 403 

Galvanism, excitation of nerves by 

(see electricity) 93, 105 

action of, upon the nerves 

(see electricity), 105 

Ganglia at the base of the enceph- 

alon, 393 

Ganglion, ophthalmic, lenticular, 

or ciliary, 419 

spheno-palatine, or Meckel's, 419 



Ganglion, otic, or Arnold's, 420 

submaxulary, 420 

cervical sympathetic, 421 

thoracic sympathetic, 422 

semilunar, 422 

lumbar and sacral sympa- 
thetic, 423 

Ganglionic nervous system (see 

sympathetic), 416 

Gasser, ganglion of, '. . .. 185 

Generative functions, connection 

of the cerebellum with, 388 

Genito-spinal centre, 438 

Glands, termination of nerves in,. . 35 

Glosso-labial paralysis, 182 

Gustation, influence of the facial 
nerve upon, 156 

Heart, influence of the spinal acces- 
sory nerves upon, 176 

direct influence of the pneu- 

mogastrics upon, 225, 411 

influence of galvanization of 

the medulla oblongata upon,. . . 411 

nerves in the substance of, . . 422 

Heat, animal, influence of the sym- 
pathetic system upon, 431, 437 

Hippocampi, 412 

Hypnogogic hallucinations, 449 

Hypoglossal nerve (see sublingual 
nerve), 178 

Idiots, development of the brain in, 338 

Intestinal secretions, influence of 
the sympathetic system upon, . . 434 

Intestines, influence of the pneu- 
mogastrics upon, 249 

Iris, influence of the motor oculi 
communis upon, through the cil- 
iary nerves, 131, 133 

reflex action of the optic 

lobes upon, .".' 398 

Irritability, nervous (see nerves),. 91 

Krause, terminal bulbs of, 42 

Language, location of the nerve- 
centre presiding over, 350 

Laryngeal nerve, superior (see 
pneumogastric), 217 

, inferior, or recurrent (see 

pneumogastric), 220 

Larynx, influence of the recurrent 
laryngeal nerves upon, 221 

Lecithine, 59 



466 



IKDEX. 



Lenticular ganglion, 419 

Ligamentum denticulatum, . ...... 260 

Liver, influence of the pneumogas- 
trics upon, 242 

Mastication, nerve of (see fifth 

nerve, small root), 139 

Meckel's ganglion, 419 

Medulla oblongata, decussation of 

the motor conductors in, 283 

physiological anatomy of, ... 402 

origin of nerves in, 404 

functions of, 405 

connection of, with respira- 
tion, 406 

influence of division of one 

lateral half of, upon respiration, 409 

vital point in, 410 

connection of, with various 

reflex acts, 411 

Meissner, corpuscles of, 39 

Meniere's disease (see ear), 387 

Mesocephalon (see tuber annulare), 398 

Motor oculi communis, 126 

physiological anatomy of, ... 127 

properties and functions of,. 128 

muscles of the eye affected 

by paralysis of, 129 

influence of, upon the iris, 131, 138 

typical case 'of paralysis of, 

in the human subject, 134 

Motor oculi externus, 136 

physiological anatomy of, ... 136 

properties and functions of,. 137 

Muscular atrophy, progressive, . . . 443 

tissue, comparison of the 

quality of, with the quality of 

brain-substance, 342 

termination of the nerves in, 29 

involuntary, termination of 

the nerves in, 34 

Myeline, 21 

Myelocytes, 55, 360 

Negative variation, 120 

Nerve-cells, varieties of, 46 

striation of the substance of, 

by the action of nitrate of silver, 48 
fibrillation of the prolonga- 
tions of, 48 

connection of, with nerve- 
fibres and with each other, 50 

Nerve-centres, structure of, 45 

accessory anatomical ele- 
ments of, , 53 



Nerve-centres, connective tissue of, 55 

blood-vessels of, 56 

perivascular canals of, 56 

trophic (see trophic), 441 

Nerve force, 97 

non-identity of, with elec- 
tricity, 98 

Nerves, structure of, 18 

medullated fibres, 19 

axis-cylinder, 21 

striation of the axis-cylinder 

by the action of nitrate of silver, 22 
fibrillation of the axis-cylin- 
der, 23 

simple, or non-medullated 

fibres, 23 

gelatinous fibres, or fibres of 

Remak, 24, 425 

accessory anatomical ele- 
ments of, 26 

perinevre of, 26 

fibrous tissue of, 27 

branching and course of, .... 28 

termination of, in voluntary 

muscles/. 29 

terminal plates of, in the 

muscles, 32 

termination of, in involuntary 

muscles, 34 

termination of, in the uterus, 35 

termination of, in glands, ... 35 

sensory, corpuscles of Paciiii, 

orofVater, 37 

sensory, tactile corpuscles, . . 39 

sensory, general mode of ter- 
mination of, 44 

reunion of fibres of different 

properties, 61 

motor and sensory, 66 

anterior and posterior roots 

of the spinal, 67 

observations of Walker, 

Mayo, Bell, and Magendie, on 

the spinal roots of, 68-73 

properties of the posterior 

spinal roots of, 79 

influence of the ganglia of the 

posterior spinal roots on the nu- 
trition of, 80 

properties of the anterior 

spinal roots of, 80 

recurrent sensibility of the 

anterior spinal roots of, 81 

mode of action of the motor 

filaments of, ; 84 



INDEX. 



467 



Nerves, independent action of the 

fibres of, 85 

mode of action of the sensory 

filaments of, 88 

sensation in members after 

amputation, 89 

irritability of, 91 

excitation of, by galvan- 
ism, 93, 105 

action of woorara upon,. ... 94 

mode of disappearance of the 

irritability of the motor filaments 

of, 96 

mode cf disappearance of the 

sensibility of, 96 

elevation of temperature in, 

during their functional activity, 104 

action of electricity upon 

(see electricity), 105 

galvanic current from the ex- 
terior to the cut surface of,. ... 113 

spinal, general description of, 122 

cranial, anatomical classifica- 
tion of> 124 

cranial, physiological classifi- 
cation of (see different cranial 
nerves under their special 

names), 125 

ciliary, 133, 419 

Yidian, 420 

cardiac sympathetic, 421 

splanchnic, 422 

solar plexus, 422 

in the substance of the heart, 422 

spiral fibres of the sympa- 
thetic, 420 

vaso-motor (see vaso-motor), 435 

trophic (see trophic), 441 

Nervous conduction, rapidity of,.. 99 
system, general considera- 
tions of, 13 

divisions of, 15 

sympathetic, ganglionic, or 

organic (see sympathetic), 416 

tissue, anatomical divisions 

of, 18 

composition of, 56 

fatty principles in, 58 

regeneration of, 60 

Nervus intercostalis, 416 j 

Xeurilemma of the spinal cord,. . . 260 

Neurine, 57 

"Neutral point, 120 

Nutrition, effects of division of the 
fifth nerve upon, 197 



(Esophagus, influence of the pneu- 

mogastrics upon, 241 

Oleo-phosphoric acid and its com- 
pounds, 59 

Olivary bodies (see medulla oblon- 

gata), 403 

Ophthalmic ganglion, 419 

Optic lobe?, functions of, 396 

extirpation of, , 397 

action of, upon the iris, 398 

Optic thalami, effects of lesion 

of, 337 

functions of, 394 

Organic system of nerves (see 
sympathetic), 41C 

Pacini, corpuscles of, 37 

Palate, influence of the facial nerve 

upon the movements of, 159 

Paralysis from disease or injury of 

the cerebellum, '. . . 390 

alternate, 147, 401 

Par vagum nerve (see pneumogas- 
tric), 203 

Patheticus nerve, 1 34 

physiological anatomy of,. . . 135 

properties and functions of, . 135 

Peduncles of the cerebellum, prop- 
erties of, 415 

Perinevre, 26 

Perivascular canal-system of the 

nerve-centres, 261 

Pharyngeal branches of the pneu- 

mogastrics (see pneumogastric), 217 
Phonation, influence of the spinal 

accessory nerve upon, 171 

influence of the recurrent 

laryngeal branches of the pneu- 

mogastrics upon, 221 

Pia mater, 260 

Pineal gland, 412 

Pituitary body, 412 

Pneumogastric nerve, 203 

physiological anatomy of, .... 204 

anastomoses of, 205 

distribution of, 206 

depressor-nerve of the circu- 
lation, 208, 231 

properties and functions of, . 211 

properties of the roots of, . . 212 

properties and functions of 

the auricular branches of, 216 

properties and functions of 

the pharyngeal branches of, ... 21 7 
properties and functions of 



468 



INDEX. 



the superior laryngeal branches 

of, 217 

Pneumogastric nerve, influence of 
the superior laryngeal branches 
of, upon deglutition, 218 

properties and functions of 

the inferior, or recurrent laryn- 
geal branches of, r 220 

influence of the ' recurrent 

laryngeal branches of, upon pho- 
nation, 221 

influence of the recurrent 

laryngeal branches of, upon the 
respiratory movements of the 
larynx, 222 

cardiac branches of, 223 

influence of section of, upon 

the circulation, 223 

influence of galvanization of, 

upon the circulation, 225 

direct influence of, upon the 

heart, 225 

reflex influence of, upon the 

circulation, 228 

properties and functions of 

the pulmonary branches of, .... 233 

effects of division of, upon 

respiration, 234 

effects of galvanization of, 

upon respiration, 238 

properties and functions of 

the cesophageal branches of, ... 241 

properties and functions of 

the abdominal branches of, .... 242 

influence of, upon the liver, . 242 

influence of, upon the stom- 
ach, 245 

influence of, upon digestion, 248 

influence of, upon the intes- 
tines, 249 

summary of the properties 

and functions of, 251 

anaesthesia produced by com- 
pression of, 256 (note) 

Pons Varolii (see tuber annulare), 398 

Protagon, 57 

Recurrent laryngeal branches of 
the pneumogastrics (see pneu- 

mogastric), . . . 220 

Recurrent sensibility of the ante- 
rior roots of the spinal nerves, 81 

Reflex action, definition of, 299 

of the brain, in dreams, 300, 449 

of the spinal cord, 300 



Reflex action, in an : vials poisoned 
with strychnine or opium, 310 

in decapitated animals, 311 

of the sympathetic system, 

429,437 

Remak, fibres of, 24, 425 

Respiration, influence of the pneu- 
mogastrics upon, 223 

sense of want of air, . . 236, 408 

effects of galvanization of the 

pneumogastrics upon, 238 

connection of the medulla ob- 

longata with, 406 

influence of dividing one lat- 
eral half of the medulla oblon- 
gata upon, 409 

Rolling and turning movements 
following injury of certain parts 
of the encephalon, 412 

Ruloff, brain of, 348 

Secretion, influence of the sympa- 
thetic system upon, 434 

Semicircular canals (see ear), .... 387 

Semilunar ganglia, 422 

Sleep, . . '. 446 

at different periods of life, . . 447 

influence of heat and cold 

upon, 448 

action of the mind during 

(see dreams), 449, 452 

condition of general sensibil- 
ity and of the special senses in, 453 

theories of, 453 

due to diminished cerebral 

circulation, 454 

production of, by compres- 
sion of the carotids, 455 

tendency to, produced by li- 
gature of both carotids, 456 

physiological repair of the 

brain during, 458 

theory that it is due to want 

of oxygen, 459 

influence of, upon various of 

the functions of the organism, 461 

Spheno-palatine ganglion, 419 

Spinal accessory nerve, 166 

physiological anatomy of, . . . 167 

properties and functions of, 169 

functions of the internal 

branch of, .' 170 

influence of, upon phonation, 171 

extirpation of, in animals, . . 172 

influence of, upon deglutition, 175 



INDEX. 



469 



Spinal accessory nerve, influence 
of, upon the heart, 176 

functions of the external 

branch of, 177 

Spinal cord, regeneration of, after 
partial exsection, 65 

physiological anatomy of, ... 264 

filum terrainale of, 265 

columns of, 266 

proportion of white to gray 

substance in, 266 

central canal of, 266 

cornua of the gray substance 

of, ...".. 267 

direction of the fibres of, ... 268 

general properties of, 273 

effects of galvanization of the 

antero-lateral columns of, . 274, 276 

effects of galvanization of 

the posterior columns of, . . 275, 276 

inexcitability and insensibil- 
ity of the gray substance of, 277, 278 

excitability and insensibility 

of the antero-lateral columns of, 278 

limits of the sensibility of the 

posterior columns of, 278 

action of, as a conductor, . . . 279 

. transmission of motor stimu- 
lus by, 280 

. situation of the motor con- 
ductors in different regions of, 281 

functions of the lateral col- 
umns of, 282 

decussation of the motor 

conductors of, in the medulla 
oblongata, 283 

decussation of the motor con- 
ductors of, in the cervical region, 283 

transmission of sensory im- 
pressions in, 285 

probable functions of the pos- 
terior white columns of, in mus- 
cular coordination, 289 

decussation of the sensory 

conductors of, 290 

summary of the action of, as 

a conductor, 295 

action of, as a nerve-centre, 298 

reflex action of (see reflex 

action), 300 

Stomach, Influence of the pneumo- 
gastrics upon, 245 

Sublingual nerve, 178 

physiological anatomy of, ... 178 

ganglion upon the root of,. . 179 



Sublingual nerve, properties and 

functions of, 180 

effects of section of, 182 

influence of, upon deglutition, 182 

Submaxillary ganglion, 420 

influence of, upon the sub- 
maxillary gland, 429 

Substantia gelatinosa of the spinal 

cord, 267 

Sympathetic nervous system,-. . . . 416 

general arrangement of,. ... 418 

cranial ganglia of, 419 

cervical ganglia of, 421 

cardiac nerves of, 421 

thoracic ganglia of, 422 

pulmonary plexus of, 422 

splanchnic nerves, 422 

solar plexus, 422 

semilunar ganglia, 422 

lumbar and pelvic ganglia of, 423 

uterine nerves of, 423 

peculiarities in the intimate 

structure of, 424 

connections of, with cerebro- 

spinal nerves, 424 

spiral fibres of, 426 

sensibility and excitability of, 426 

influence of stimulation of 

parts of, upon the intestines,. . . 428 
influence of, upon the sub- 
maxillary gland, 429 

reflex action in, 429, 437 

functions of, 430. 

division of the sympathetic 

cord in the neck, 431 

influence of, upon animal 

heat, secretion of sweat, etc., 431, 437 
influence of, upon the circu- 
lation, 432,433 

influence of, upon secretion, 434 

influence of, upon the urine, 434 
influence of, upon the intes- 
tinal secretions, 434 

influence of, upon certain 

psychical acts, 438 

cases of disease or injury of, 

in the human subject, 440 

experiments upon, in a de- 
capitated criminal, 440 

Tactile corpuscles, 39 

Taste (see gustation), 156 

Tentorium, 259 

Terminal bulbs of the sensory 
nerves, . . ... 42 



470 



INDEX. 



Testicles, movements of, produced 
by irritation of the cerebel- 
lum, 363, 389 

Trifacial nerve, 184 

physiological anatomy of, ... 184 

Gasserian ganglion of, 1 85 

properties and functions of, 189 

division of, in the cranial 

cavity, 190 

immediate effects of division 

of, 192 

exquisite sensibility of, 193 

remote effects of division of, 196 

effects of division of, upon 

nutrition, 198 

paralysis of, in the human 

subject, 201 

Trochlearis nerve (see patheticus), 134 
Trophic centres and nerves, so 

called, 441 

progressive muscular atro- 
phy, 443 

Tuber annulare, properties and 

functions of, 398 

alternate paralysis in lesions 

of, 147,401 

Tubercula quadrigemina, functions 

of, 396 

extirpation of, 397 

action of, upon the iris, .... 398 

Urine, influence of the sympa- 
thetic system upon, 434 

Uterus, movements of, produced by 
irritation of the cerebellum, 363, 389 



Uterus, nerves of, 423 

Uvula, influence of the facial nerve 
upon the movements of 162 

Vagus nerve (see pneumogastric), 203 
Vasa deferentia, movements of, 
produced by irritation of the 

cerebellum, 363 

Vaso-motor nerves, 435 

derivation of, from the cere- 

bro-spinal centres, 436, 440 

Vater, corpuscles of, 37 

Velum interpositum, 260 

Ventricle, fourth, 360, 403 

Ventricles of the brain, 412 

Vertigo, in cases of disease of the 
cerebellum and of disease of the 

semicircular canals, 387 

Vidian nerve, 420 

Vital #oint in the medulla oblon- 

gata, 410 

Voice, influence of the spinal ac- 
cessory nerve upon (see phona- 

tion),.. 171 

influence of the recurrent 

laryngeal nerves upon (see pho- 
nation), 221 

Wagner, corpuscles of, 39 

Webster, brain of, 348 

Woorara, action of, upon the 

nerves, 94 

Wrisberg, nerve of. 145, 156 

ganglion upon th,e root of,. . 148 



CATALOGUE 

OP 

MEDICAL WORKS 



ANSTIE. 

Neuralgia, and Diseases which resemble it. 

By FRANCIS E. AXSTIE, M. D., F. R. C. P., 

Senior Assistant Physician to Westminster Hospital : Lecturer on Materia Medica in West' 
minster Hospital School : and Physician to the Belgrave Hospital for Children : Editor 
of "The Practitioner" (London), etc. 

1 vol., 12mo. Cloth, $2.50. 

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more practical information and is fuller of useful suggestions." Medical Record. 

BARKER. 
On Sea-sickness. 

By FORDYCE BARKER, M. D., 

Clinical Professor of Midwifery and the Diseases of Women in the Bellevue Hospital 
Medical College, etc. 

1 vol., 16mo. 36 pp. Flexible Cloth, 75 cents. 

Reprinted from the NEW YORK MEDICAL, JOTTRNAL. By reason of the great demand 
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BARNES. 

Obstetric Operations, including the Treatment 
of Haemorrhage. 

By ROBERT BARNES, M. D., F. R. C. P., LOXDOX, 

Obstetric Physician to and Lecturer on Midwifery and the Diseases of Women and Chil- 
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sicians and to the Royal College of Surgeons; formerly Obstetric Physician to the 
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WITH ADDITIONS, by BENJAMIN F. DAWSON, M. D., 

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Second American Edition. 1 vol., 8vo. 503 pp. Cloth, $4.50. 

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Bellevue and Charity Hospital Reports. 

The volume of Bellovue and Charity Hospital Reports 
for 1870, containing valuable contributions from 

ISAAC E. TAYLOR, M. D., WILLIAM A. HAMMOND, M. D., 

AUSTIN FLINT, M. D., T. GAILLARD THOMAS, M. D., 

LEWIS A. SAYRE, M. D., FRANK H. HAMILTON, M. D., 

and others. 

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BENNET 
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the Mediterranean j or, the Rimer a, Mentone, Italy, 
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ter Climates. 

By J. HENRY BENNET, M. D., 

Member of the Royal College of Physicians, London; late Physician-Accoucher to the 
Royal Free Hospital; Doctor of Medicine of the University of Paris; formerly Resi- 
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On the Treatment of Pulmonary Con- 

sumption, by Hygiene, Climate,' and Medicine, in its 
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By JAMES HENRY BENNET, M. D., 

Member of the Royal College of Physicians, London; Doctor of Medicine of the University 

of Paris, etc., etc. 

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BILLROTH. 
General Surgical Pathology and The- 

rapeuticS) in Fifty Lectures. A Text-book for Students 
and Physicians. 

By Dr. THEODOR BILLROTH, 

Professor of Surgery in Vienna. 

Translated from the Fourth German Edition, with the special permission 
of the Author, by 

CHARLES E. HACKLEY, A. M., M. D., 

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1 vol., 8vo. 676 pp., and 152 Woodcuts. Cloth, $5.00. 

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SPECniEI OF rLLTJBTBATIONS. 




Mammary Cancer, acinons form, magnified 60 diameters. 

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COMBE. 

The Management of Infancy, Physiologi- 
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By ANDREW COMBE, M. D. 

REVISED AND EDITED 

By SIR JAMES CLARK, K. 0. B., M. D., F. R. S., 

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First American from the Tenth London Edition. 1 vol., 12mo. 302 pp. 

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DAVIS. 

Conservative Surgery, as exhibited in remedying 
some of the Mechanical Causes that operate injuri- 
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By HE^RY G. DAVIS, M. D., 

Member of the American Medical Association, etc., etc. 
1 vol., 8vo. 315 pp. Cloth, $3.00. 

The Author has enjoyed rare facilities for the study and treatment 
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The style is unpretending, but trenchant, graphic, and, best of all, quite intelli- 
gible." Medical Record. 



D. Appleton & Co?s Medical Publications. 

FLINT. 

The Physiology of Man. Designed to rep- 
resent the Existing State of Physiological Science as 
applied to the Functions of the Human Body, 
By AUSTIN FLINT, JE., M. D., 

Professor of Physiology and Microscopy in the Bellevue Hospital Medical College, and in the 
Long Island" College Hospital; Fellow of the New York Academy of Medicine ; Microscopist 
to Bellevue Hospital 

In Five Volumes. 8vo. Tinted Paper. 

Yolume I. The Blood ; Circulation; Respiration. 

8vo. 502 pp. Cloth, $4.50. 

SPECIMEN OF ILLtTSTBATIONS. 




Ducts and Acini of the Mammary Organs. 

" If the remaining portions of this work are compiled with the same care and 
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and, as a book of reference, invaluable in the hands of the anatomist and physi- 
ologist." Dublin Quarterly Journal of Medical Science. 

" The complete work will prove a valuable addition to our systematic treatises 
on human physiology." The Lancet. 

" To those who desire to get in one volume a concise and clear, and at the 
same time sufficiently full resume of ' the existing state of physiological science,' 
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cal art it deserves a prominent place upon our library-shelves. Messrs. Appleton 
& Co. deserve the thanks of the profession for the very handsome style in which 
they issue medical works. They give us hope of a time when it will be very 
generally believed by publishers that physicians' eyes are worth saving." Medi- 
cal Gazette. 



D. Appleton & CoSs Medical Publications. 

Flint's Physiology. Volume II. Alimenta- 
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8vo. 556 pp. Cloth, $4.50. 

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" The leading subjects treated of are presented in distinct parts, each of which 
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Volume III. Secretion ; Excretion ; Ductless Glands ; Nu- 
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8vo. 526 pp. Cloth, $4.50. 

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authority is admissible. New York Times. 

Volume IV. The Nervous System. 

This volume is now ready. It is a work of great interest, and, in 
conjunction with the " Treatise on Diseases of the Nervous System," by 
Dr. Wm. A. Hammond, constitutes a complete work on " The Physiology 
and Pathology of the Nervous System." 

Volume V. Generation. (In press.) 



1J. Appleton & CoSs Medical Publications. 

FLINT. 
Manual of Chemical Examination of 

the Urine in Disease. With Brief Directions for tJie 
Examination of the most Common Varieties of Uri- 
nary Calculi. 

By AUSTIN FLINT, JR., M. D., 

Professor of Physiology and Microscopy in the Bellevue Hospital Medical College ; Fellow of the 
New York Academy of Medicine; Member of the Medical Society of the County of New 
York ; Resident Member of the Lyceum of Natural History in the City of New York, etc. 

Third Edition, revised and corrected. 1 vol., 12mo. 77 pp. Cloth, $1.00. 

The chief aim of this little work is to enable the busy practitioner to 
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to the utmost simplicity that is consistent with accuracy. 

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"Eminently practical." Detroit Review of Medicine. 

On the Physiological Effects of Severe 

and Protracted Muscular Exercise. With Special Ref- 
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By AUSTIN FLINT, JR., M.D., 

Professor of Physiology in the Bellevue Hospital Medical College, New York, etc., etc. 

1 vol., 8vo. 91 pp. Cloth, $2.00. 

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of Surgical Anatomy; W. H. Van Buren, M. D., Professor of Principles 
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" This work will be found interesting to every physician. A number of im- 
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D. Appleton & CoSs Medical Publications. 

HAMMOND. 
A Treatise on Diseases of the Nervous 

System. 

By WILLIAM A. HAMMOND, M. D., 

Professor of Diseases of the Mind and Nervous System, and of Clinical Medicine, in the Bellevue 
Hospital Medical College ; Physician-in-Chief to the New York State Hospital for Diseases 
of the Nervous System, etc., etc. 

SECOND EDITION, REVISED AND CORRECTED. 

With Forty-five Illustrations. 1 vol., 8vo. 750 pp. Cloth, $5.00. 

The treatise embraces an introductory chapter, which relates to the 
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the third, cerebro-spinal diseases ; the fourth, diseases of nerve-cells ; 
and the fifth, diseases of the peripheral nerves. One feature which may 
be claimed for the work is, that it rests, to a great extent, upon the per- 
sonal observation and experience of the author, and is therefore no mere 
compilation. 



" The author's clear and terse style of diction renders the book exceedingly 
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" The work is replete with useful knowledge, and every physician who expects 
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Cincinnati Lancet and Observer. 

" This is unquestionably the most complete treatise on the diseases to which 
it is devoted that has yet appeared in the English language ; and its value is 
much increased by the fact that Dr. Hammond has mainly based it on his own 
experience and practice, which, we need hardly remind our readers, have been 
very extensive." London Medical Times and Gazette. 

" Free from useless verbiage and obscurity, it is evidently the work of a 
man who knows what he is writing about, and knows how to write about it." 
Chicago Medical Journal. 



D. Applet on & Co?s Medical Publications. 

HOLLAND. 
Recollections of Past Life, 

By SIR HENRY HOLLAXD, Bart., M. D., F. R. S M K. C. B., etc., 
President of the Royal Institution of Great Britain, Physician-in-Ordinary to the Queen, 

etc., etc. 

1 vol., 12mo, 351 pp. Price, Cloth, $2.00. 

A very entertaining and instructive narrative, partaking somewhat of the nature of 
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" His memory was is, we may say, for he is still alive and in possession of all his 
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active manner, in the midst of the best society, which the world has to offer, must neces- 
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his memory lost its freshness before recalling some of the incidents in it." The Sew 
York Times. 

HOWE. 
Emergencies, and How to Treat Them. 

The Etiology, Pathology, and Treatment of Accidents, 
Diseases, and Cases of, Poisoning, which demand 
Prompt Attention. Designed for Students and Prac- 
titioners of Medicine. 

By JOSEPH W. HOWE, M. D., 

Visiting Surgeon to Charity Hospital ; Lecturer on Surgery in the Medical Department of 
the University of New York, etc. 

1 vol., 8vo. 265 pp. Cloth, $3.00. 

This volume is designed as a guide in the treatment of cases of emergency occurring in 
medical, surgical, or obstetrical practice. It combines all the important subjects, giving 
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and American authorities. 

"The style is concise, perspicuous, and definite. Each article is written as though that 
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herma, are particularly clear and practical, and furnish all the information required in the 
managemant of those urgent cases. 

"It will be found invaluable to students and young practitioners, in supplvin"- them 
with an epitome of useful knowledge obtainable from no other single work: while'to the 
older members of the profession it will serve as a reliable and l ready remembrancer ' "- 
77ie Medtcal Etcord. 



D. Appleton & Go's Medical Publications. 

HUXLEY AND YOUMANS. 
The Elements of Physiology and 

Hygiene. With Numerous Illustrations. 

By THOMAS H. HUXLEY, LL. D., F. E. S., and 

WILLIAM JAY YOUMANS, M.D. 

1 vol., 12mo. 420 pp, $1,75. 

A text-book for educational institutions, and a valuable elementary 
work for students of medicine. The greater portion is from the pen of 
Professor Huxley, adapted by Dr. Youmans to the circumstances and 
requirements of American education. 

" A valuable contribution to anatomical and physiological science." Religious 
Telescope. 

"A clear and well-arranged work, embracing the latest discoveries and ac- 
cepted theories." Buffalo Commercial. 

" Teeming with information concerning the human physical economy." 
Evening Journal. 

HUXLEY. 
The Anatomy of Vertebrated Animals, 

By THOMAS HENRY HlfXLEY, LL. D., F. R. S., 

Author of "Man's Place in Nature," "On the Origin of Species," " Lay Sermons and 

Addresses," etc. 

1 vol., 12mo. Cloth, $2-00. 

The former works of Prof. Huxley leave no room for doubt as to the impor- 
tance and value of his new volume. It is one which will be very acceptable to all 
who are interested in the subject of which it treats. 

SPECIMEN OF ILLUSTRATIONS. 




The Alligator Terrapene (Chelydra Serpentina). 



"This long-expected work will "be cordially welcomed "by all students and teachers of 
Comparative Anatomy as a compendious, reliable, and, notwithstanding its email dimen- 
sions, most comprehensive guide on the subject of w^iich it treats. To praise or to criti- 
cise the work of so accomplished a master of his favorite science would 90 equally out of 
place. It is enough to say that it realizes, in a remarkable degree, the anticipations which 
have been formed of it; and that it presents an extraordinary combination of wide, gen- 
eral views, with the clear, accurate, and succinct statement of a prodigious number of 
individual facts." Nature. 



D. Appleton & Co?s Medical Publications. 

JOHNSOK 

The Chemistry of Common Life. 

Illustrated with numerous Wood Engravings. 
By JAMES F. JOHNSON, M. A., F. R. S., F. G. S., ETC., ETC., 

Author of "Lectures on Agricultural Chemistry and Geology," "A Catechism of Agricultural 
Chemistry and Geology,' 1 etc, 

2 vols., 12mo. Cloth, $3.00. 

It has been the object of the author in this work to exhibit the 
present condition of chemical knowledge, and of matured scientific 
opinion, upon the subjects to which it is devoted. The reader will not 
be surprised, therefore, should he find in it some things which differ 
from what is to be found in other popular works already in his hands or 
on the shelves of his library. 

LETTERMAN. 
Medical Recollections of the Army of 

the Potomac. 

By JONATHAN LETTERMAN, M. D., 

Late Surgeon U. S. A^, and Medical Director of the Army of the Potomac. 

1 vol., 8vo. 194 pp. Cloth, $1.00. 

" This account of the medical department of the Army of the Poto- 
mac has been prepared, amid pressing engagements, in the hope that 
the labors of the medical officers of that army may be known to an in- 
telligent people, with whom to know is to appreciate ; and as an affec 
tionate tribute to many, long my zealous and efficient colleagues, who, 
in days of trial and danger, which have passed, let us hope never to re- 
turn, evinced their devotion to their country and to the cause of hu- 
manity, without hope of promotion or expectation of reward." Preface. 

" We venture to assert that but few who open this volume of medical annals, 
pregnant as they are with instruction, will care to do otherwise than finish them 
at a sitting." Medical Record. 

" A graceful and affectionate tribute." N". T. Medical Journal 

LEWES. 
The Physiology of Common Life. 

By GEORGE HENRY LEWES, 

Author of "Seaside Studies," "Life of Goethe," etc. 

2 vols., 12mo. Cloth, $3.00. 

The object of this work differs from that of all others on popular 
science in its attempt to meet the wants of the student, while meeting 
those of the general reader, who is supposed to be wholly unacquainted 
with anatomy and physiology. 



D. Appleton <& CoSs Medical Publications. 

MAUDSLEY. 
The Physiology and Pathology of the 

Mind. 

By HENRY MAUDSLEY, M. D., LOITDON, 

Physician to the "West London Hospital; Honorary Member of the Medico-Psychological Society 
of Paris ; formerly Resident Physician of the Manchester Eoyal Lunatic Hospital, etc. 

1 vol., 8vo. 442 pp. Cloth, $3,50. 

This work aims, in the first place, to treat of mental phenomena from 
a physiological rather than from a metaphysical point of view ; and, 
secondly, to bring the manifold instructive instances presented by the 
unsound mind to bear upon the interpretation of the obscure problems 
of mental science. 

" Dr. Maudsley has had the courage to undertake, and the skill to execute, 
what is, at least in English, an original enterprise." London Saturday Review. 

" It is so full of sensible reflections and sound truths that their wide dissemi- 
nation could not but be of benefit to all thinking persons." PsychologicalJournal. 

"Unquestionably one of the ablest and most important works on the subject 
of which it treats that has ever appeared, and does credit to his philosophical 
acumen and accurate observation." Medical Record. 

" We lay down the book with admiration, and we commend it most earnestly 
to our readers as a work of extraordinary merit and originality one of those 
productions that are evolved only occasionally in the lapse of years, and that 
serve to mark actual and very decided advances in knowledge and science." 
N. Y. Medical Journal. 

Body and Mind : An Inquiry into their Con- 
nection and Mutual Influence, specially in reference 
to Mental Disorders ; ~being the Gulstonian Lectures 
for 1870, delivered "before the Royal College of 
Physicians. With Appendix. 

By HENRY MAUDSLEY, M. D., LONDON, 

Fellow of the Eoyal College of Physicians ; Professor of Medical Jurisprudence in University Col- 
lege. London ; President-elect 'of the Medico-Psychological Association ; Honorary Member of 
the Medico-Psychological Society of Paris, of the Imperial Society of Physicians of Vienna, 
and of the Society for the Promotion of Psychiatry and Forensic Psychology of Vienna ; 
formerly Besident Physician of the Manchester Eoyal Lunatic Asylum, etc., etc. 

1 vol., 12mo. 155 pp. Cloth, $1.00. 

The general plan of this work may be described as being to bring 
man, both in his physical and mental relations, as much as possible with- 
in the scope of scientific inquiry. 

" A representative work, which every one must study who desires to know 
what is doing in the way of real progress, and not mere chatter, about mental 
physiology and pathology." The Lancet. 

" It distinctly marks a step in the progress of scientific psychology." The 
Practitioner. 



D. Appleton & CoSs Medical Publications. 

MAKKOE. 

A Treatise on Diseases of the Bones. 

By THOMAS M. MARKOE, M. 0., 
Professor of Surgery in the College of Physicians and Surgeons, New York, etc. 

WITH NUMEROUS ILLUSTRATIONS. 
1 vol. 8vo. Cloth, $4.50. 

SPECIMEN OF ILLUSTRATIONS. 




This valuable work is a treatise on Diseases of the Bones, embracing their 
structural changas as affected by disease, their clinical history and treatment, in- 
cluding also an account of the various tumors which grow in or upon them. 
Xone of the injuries of bone are included in its scope, and no joint diseases, ex- 
cepting where the condition of the bone is a prime factor in the problem of 
disease. As the work of an eminent surgeon of large and varied experience, it 
imy be regarded as the best on the subject, and a valuable contribution to medi- 
cal literature. 

" The book which I now offer to my professional brethren contains the substance of 
the lectures which I have delivered during the past twelve years at the college. ... I 
have followed the leadings of my own studies and observations, dwelling more on those 
branches where I had seen and studied most, and perhaps too much neglecting others 
where my own experience was more barren, and therefore to me less interesting. I have 
endeavored, however, to make up the deficiencies of my own knowledge by the free use of 
the materials scattered so richly through our periodical literature, which scattered 
leaves it is the right and the duty of the systematic writer to collect and to embody in 
any account he may offer of the state of a science at any given period." Extract from 
Author's Preface. 



D. Appleton & CoSs Medical Publications. 

MEYER 
Electricity in its Relations to Practical 

Medicine. 

By DE. MORITZ MEYER, 

Eoyal Counsellor of Health, etc. 

Translated from the Third German Edition, with Notes and Additions, 
A New and Revised Edition, 

By WILLIAM A. HAMMOND, M. D., 

Professor of Diseases of the Mind and Nervous System, and of Clinical Medicine, in the Bellevue 
Hospital Medical College; Vice-President of the Academy of Mental Sciences, National 
Institute of Letters, Arts, and Sciences ; late Surgeon-General U. S. A., etc. 

1 vol., 8vo. 497 pp. Cloth, $4.50. 

" It is the duty of every physician to study the action of electricity, 
to become acquainted with its value in therapeutics, and to follow the 
improvements that are being made in the apparatus for its application in 
medicine, that he may be able to choose the one best adapted to the 
treatment of individual cases, and to test a remedy fairly and without 
prejudice, which already, especially in nervous diseases, has been used 
with the best results, and which promises to yield an abundant harvest 
in a still broader domain." From Author's Preface. 

SPECIMEN OF ILH78TBATION8. 




Saxton-Ettinghausen Apparatus. 

" Those who do not read German are under great obligations to William A. 
Hammond, who has given them not only an excellent translation of a most ex- 
cellent work, but has given us much valuable information and many suggestions 
from his own personal experience." Medical Record. 

" Dr. Moritz Meyer, of Berlin, has been for more than twenty years a laborious 
and conscientious student of the application of electricity to practical ^ medicine, 
and the results of his labors are given in this volume. Dr. Hammond, in making 
a translation of the third German edition, has done a real service to the profession 
of this country and of Great Britain. Plainly and concisely written, and simply 
and clearly arranged, it contains just what the physician wants to know on the 
subject." N. T. Medical Journal 

" It is destined to fill a want long felt by physicians in this country." Journal 
of Obstetrics. 



D. Appleton & (70. 's Medical Publications. 

NIEMEYER 
A Text-Book of Practical Medicine. 

With Particular Reference to Physiology and Patho- 
logical Anatomy. 

By the late Dr. FELIX YON NIEMEYER, 

Professor of Pathology and Therapeutics; Director of the Medical Clinic of the University of 

Tubingen. 

Translated from tlie Eighth German Edition, by special permission of 

the Author, 

By GEORGE H. HUMPHREYS, M. D., 

Late one of the Physicians to the Bureau of Medical and Surgical Relief at Bellevue Hospital for 
the Out-door Poor ; Fellow of the New York Academy of Medicine, etc., 

and 
CHARLES E. HACKLEY, M. D., 

One of the Physicians to the New York Hospital; one of the Surgeons to the New York Eye 
and Ear Infirmary ; Fellow of the New York Academy of Medicine, etc. 

Bevised Edition. 2 vols., 8vo, 1,528 pp. Cloth, $9.00 ; Sheep, $11.00. 

The author undertakes, first, to give a picture of disease which shall 
be as lifelike and faithful to nature as possible, instead of being a mere 
theoretical scheme; secondly, so to utilize the more recent advances 
of pathological anatomy, physiology, and physiological chemistry, as to 
furnish a clearer insight into the various processes of disease. 

The work has met with the most flattering reception and deserved 
success ; has been adopted as a text-book in many of the medical colleges 
both in this country and in Europe; and has received the very highest 
encomiums from the medical and secular press. 

"It is comprehensive and concise, and is characterized by clearness and 
originality." Dublin Quarterly Journal of Medicine. 

" Its author is learned in medical literature ; he has arranged his materials 
with care and judgment, and has thought over them." The Lancet. 

"As a full, systematic, and thoroughly practical guide for the student and 
physician, it is not excelled by any similar treatise in any language." Appletons 1 
Journal. 

" The author is an accomplished pathologist and practical physician ; he is not 
only capable of appreciating the new discoveries, which during the last ten years 
have been unusually numerous and important hi scientific and practical medicine, 
but, by his clinical experience, he can put these new views to a practical test, and 
give judgment regarding them." Edinburgh Medical Journal. 

" From its general excellence, we are disposed to think that it will soon take 
its place among the recognized text-books." American Quarterly Journal of 
Medical Sciences. 

" The first inquiry in this country regarding a German book generally is, ' la 
it a work of practical value ? " Without stopping to consider the justness of the 
American idea of the ' practical,' we can unhesitatingly answer, ' It is ! ' " New 
York Medical Journal. 

" The author has the power of sifting the tares from the wheat a matter of 
the greatest importance hi a text-book for students." British Medical Journal. 

" Whatever exalted opinion our countrymen may have of the author's talents 
of observation and his practical good sense, his text-book will not disappoint 
them, while those who are so unfortunate as to know him only by name, have hi 
store a rich treat." New York Medical Record, 



D. Appleton & CoSs Medical Publications. 

NEUMANN. 
Hand-Book of Skin Diseases. 

By DR. ISIDOR NEUMANN, 
Lecturer on Skin Diseases in the Royal University of Vienna. 

Translated from advanced sheets of the second edition, furnished by the 
Author; with Notas, 

By LUCIUS D. BULKLEY, A. M., M. D., 

Surgeon to the New York Dispensary, Department of Venereal and Skin Diseases ; Assist- 
ant to the Skin Clinic of the College of Physicians and Surgeons, New York; Mem- 
ber of the New York Dermatological Society, etc., etc. 

1 vol., 8vo. AbDut 45D pages and 66 Woodcuts. Cloth, $4.00. 

SPECIMEN OF ILLUSTRATIONS. 




Section of skin from a bald head. 

Prof. Neumann ranks second only to Hebra, whose assistant he was for many years, 
and his work may be considered as a fair exponent of the German practice of Dermatolo- 
gy. The book is abundantly illustrated with plates of the histology and pathology of the 
skin. The translator has endeavored, by means of notes from French, English, and Ameri- 
can sources, to make the work valuable to the student as well as to the practitioner. 

"It is a work which I shall heartily recommend to my class of students at the Univer- 
sity of Pennsylvania, and one which I feel sure will do much toward enlightening the pro- 
fession on this subject." Louis A. Duhring. 

" I know it to be a good book, and I am sure that it is well translated ; and it is inter- 
esting to find it illustrated by references to the views of co-laborers in the same field." 
Erasmus Wilson. 

" So complete as to render it a mo?t useful book of reference." T. McCatt Anderson. 

" There certainly is no work extant which deals so thoroughly with the Pathological 
Anatomy of the Skin as does this hand-book." N. Y. Medical Record. 

" The original notes by Dr. Bulkley are very practical, and are an important adjunct to 
the text. ... I anticipate for it a wide circulation."^^ DurJcee. Boston. 

" I have already twice expressed my favorable opinion of the book in print, and am 
glad that it is given to the public at last." James C. White, Boston. 

" More than two years ago we noticed Dr. Neumann's admirable work in its original 
shape ; and we are therefore absolved from the necessity of saying more than to repeat 
our strong recommendation of it to English readers." Practitioner. 



D. Appleton & (70. 's Medical Publications. 

HOLLAND. 
Recollections of Past Life, 

By SIR HENRY HOLLAND, Bart, M. D., F. R. S., K. C. B., etc., 
President of the Royal Institution of Great Britain, Physician-in-Ordinary to the Queen, 

etc., etc. 

1 vol., 12mo, 351 pp. Price, Cloth, $2.00. 

A very entertaining and instructive narrative, partaking somewhat of the nature of 
autobiography and yet distinct from it, in this, that its chief object, as alleged by the 
writer, is not so much to recount the events of his own life, as to perform the office of 
chronicler for others with whom he came in contact and was long associated. 

The "Life of Sir Henry Holland " is one to be recollected, and he has not erred in giv- 
ing an outline ot it to the public." The Lancet. 

" His memory was is, we may say, for be is still alive and in possession of all his 
faculties stored with recollections of the most eminent men and women of this cen- 
tury. ... A life extending over a period of eighty-four years, and passed in the most 
active manner, in the midst of the best society, which the world has to offer, must neces- 
sarily be fall of singular interest ; and Sir Henry Holland has fortunately not waited until 
his memory lost its freshness before recalling some of the incidents in it." The New 
York Times. 

HOWE. 
Emergencies, and How to Treat Them. 

The Etiology, Pathology, and Treatment of Accidents, 
Diseases, and Cases of Poisoning, which demand 
Prompt Attention. Designed for Students and Prac- 
titioners of Medicine. 

By JOSEPH W. HOWE, M. D., 

Visiting Surgeon to Charity Hospital ; Lecturer on Surgery in the Medical Department of 
the University of New York, etc. 

1 vol., 8vo. 265 pp. Cloth, $3.00, 

This volume is designed as a guide in the treatment of cases of emergency occurring in 
medical, surgical, or obstetrical practice. It combines all the important subjects, giving 
special prominence to points of practical interest in preference to theoretical considera- 
tions, and uniting, with the results of personal observation, the latest views of Enropean 
and American authorities. 

"The style is concise, perspicuous, and definite. Each article is written as though that 
particular emergency were present; there is no waste of words, nor temporizing with 
remedies of doubtful efficacy. The articles on oedema glottidis. asphvxia, and strangulated 
hernia, are particularly clear and practical, and furnish all the information required 7 in the 
management of those urgent cases 

_ "It will be found invaluable to students and young practitioners, in supplying them 
with an epitome of useful knowled<re obtainable from no other single work: while" to the 
older members of the profession it will serve as a reliable and ' ready remembrancer ' "- 
The Medical Record. 



D. Appleton & Go's Medical Publications. 

MAUDSLEY. 
The Physiology and Pathology of the 

Mind. 

By HENRY MAUDSLEY, M. D., LOITDON, 

Physician to the West London Hospital; Honorary Member of the Medico-Psychological Society 
of Paris ; formerly Eesident Physician of the Manchester Koyal Lunatic Hospital, etc. 

1 vol., 8vo. 442 pp. Cloth, $3.50. 

This work aims, in the first place, to treat of mental phenomena from 
a- physiological rather than from a metaphysical point of view ; and, 
secondly, to bring the manifold instructive instances presented by the 
unsound mind to bear upon the interpretation of the obscure problems 
of mental science. 

" Dr. Maudsley has had the courage to undertake, and the skill to execute, 
what is, at least in English, an original enterprise." London Saturday Review. 

" It is so full of sensible reflections and sound truths that their wide dissemi- 
nation could not but be of benefit to all thinking persons." PsychologicalJournal. 

" Unquestionably one of the ablest and most important works on the subject 
of which it treats that has ever appeared, and does credit to his philosophical 
acumen and accurate observation." Medical Record, 

" We lay down the book with admiration, and we commend it most earnestly 
to our readers as a work of extraordinary merit and originality one of those 
productions that are evolved only occasionally in the lapse of years, and that 
serve to mark actual and very decided advances in knowledge and science." 
N~. Y. Medical Journal. 



Body 



and Mind I An Inquiry into their Con- 
nection and Mutual Influence, specially in reference 
to Mental Disorders ; being the Gulstonian Lectures 
for 1870, delivered before the Royal College of 
Physicians. With Appendix. 

By HENRY MAUDSLEY, M. D., LONDON, 

Fellow of the Eoyal College of Physicians ; Professor of Medical Jurisprudence in University Col- 
lege, London ; President-elect of the Medico-Psychological Association ; Honorary Member of 
the Medico-Psychological Society of Paris, of the Imperial Society of Physicians of Vienna, 
and of the Society for the Promotion of Psychiatry and Forensic Psychology of Vienna ; 
formerly Kesident Physician of the Manchester Royal Lunatic Asylum, etc., etc. 

1 vol., 12mo. 155 pp. Cloth, $1.00. 

The general plan of this work may be described as being to bring 
man, both in his physical and mental relations, as much as possible with- 
in the scope of scientific inquiry. 

" A representative work, which every one must study who desires to know 
what is doing in the way of real progress, and not mere chatter, about mental 
physiology and pathology." The Lancet. 

"It distinctly marks a step in the progress of scientific psychology." The 
Practitioner. 



D. Appleton & Co?s Medical Publications. 

MAKKOE. 

A Treatise on Diseases of the Bones. 

By THOMAS M. MARKOE, M. D., 

Professor of Surgery in the College of Physicians and Surgeons, New York, etc. 

WITH NUMEROUS ILLUSTRATIONS.' 
1 vol. 8vo. Cloth, $4.50. 



SPECIMEN OF ILLUSTRATIONS. 




This valuable work is a treatise on Diseases of the Bones, embracing their 
structural changes as affected by disease, their clinical history and treatment, in- 
cluding also an account of the various tumors which grow in or upon them. 
None of the injuries of bone are included in its scope, and no joint diseases, ex- 
cepting where the condition of the bone is a prime factor in the problem of 
disease. As the work of an eminent surgeon of large and varied experience, it 
may be regarded as the best on the subject, and a valuable contribution to medi- 
cal literature. 

"The book which I now offer to my professional brethren contains the substance of 
the lectures which I have deliverer] duringr the past twelve years at the college. ... I 
have followed the leadinss of my own studies and observations, dwelling more on those 
branches where I had seen and studied most, and perhaps too much neglecting others 
where my own experience was more barren, and therefore to me less interesting. I have 
endeavored, however, to make up the deficiencies of my own knowledge by the free use of 
the materials scattered so richly through our periodical literature, which scattered 
leaves it is the right and the duty of the systematic writer to collect and to embody in 
any account he may offer of the state of a science at any given period." Extract from 
Author' 1 s Preface. 



D. Appleton & CoSs Medical Publications. 

MEYER 
Electricity in its Relations to Practical 

Medicine. 

By DE. MOKITZ MEYER, 

Eoyal Counsellor of Health, etc. 

Translated from, the Third German Edition, with Notes and Additions, 
A New and Revised Edition, 

By WILLIAM A. HAMMOND, M. D., 

Professor of Diseases of the Mind and Nervous System, and of Clinical Medicine, in the Bellevue 
Hospital Medical College; Vice-President of the Academy of Mental Sciences, National 
Institute of Letters, Arts, and Sciences ; late Surgeon-General U. S. A., etc. 

1 vol., 8vo. 497 pp. Cloth, $4.50. 

"It is the duty of every physician to study the action of electricity, 
to become acquainted with its value in therapeutics, and to follow the 
improvements that are being made in the apparatus for its application in 
medicine, that he may be able to choose the one best adapted to the 
treatment of individual cases, and to test a remedy fairly and without 
prejudice, which already, especially in nervous diseases, has been used 
with the best results, and which promises to yield an abundant harvest 
in a still broader domain." From Author's Preface. 



SPECIMEN OP ILLUSTRATIONS. 




Saxton-Ettinghausen Apparatus. 

" Those who do not read German are under great obligations to William A. 
Hammond, who has given them not only an excellent translation of a most ex- 
cellent work, but has given us much valuable information and many suggestion? 
from his own personal experience. "-^Medical Record. 

" Dr. Moritz Meyer, of Berlin, has been for more than twenty years a laborious 
and conscientious student of the application of electricity to practical medicine, 
and the results of his labors are given in this volume. Dr. Hammond, in making 
a translation of the third German edition, has done a real service to the profession 
of this country and of Great Britain. Plainly and concisely written, and simply 
and clearly arranged, it contains just what the physician wants to know on the 
subject." N. T. Medical Journal. 

" It is destined to fill a want long felt by physicians in this country." Journal 
of Obstetric*. 



D. Appleton & CoSs Medical Publications. 

NIEMEYER. 
A Text-Book of Practical Medicine. 

With Particular Reference to Physiology and Patho- 
logical Anatomy. 

By the late Dr. FELIX VON NIEMEYEK, 

Professor of Pathology and Therapeutics; Director of the Medical Clinic of the University of 

Tubingen. 

Translated from the Eighth German Edition, by special permission of 

the Author, 

By GEORGE H. HUMPHREYS, M. D., 

Late one of the Physicians to the Bureau of Medical and Surgical Relief at BeUevue Hospital for 
the Out-door Poor ; Fellow of the New York Academy of Medicine, efcx, 

and 

CHARLES E. HACKLEY, M. D., 

One of the Physicians to the New York Hospital; one of the Surgeons to the New York Eye 
and Ear Infirmary ; Fellow of the New York Academy of Medicine, etc. 

Revised Edition. 2 vols., 8vo. 1,528 pp. Cloth, $9.00 ; Sheep, $11.00. 

The author undertakes, first, to give a picture of disease which shall 
be as lifelike and faithful to nature as possible, instead of being a mere 
theoretical scheme ; secondly, so to utilize the more recent advances 
of pathological anatomy, physiology, and physiological chemistry, as to 
furnish a clearer insight into the various processes of disease. 

The work has met with the most flattering reception and deserved 
success ; has been adopted as a text-book in many of the medical colleges 
both in this country and in Europe; and has received the very highest 
encomiums from the medical and secular press 

" It is comprehensive and concise, and is characterized by clearness and 
originality." Dublin Quarterly Journal of Medicine. 

u Its author is learned in medical literature ; he has arranged his materials 
with care and judgment, and has thought over them/'-^^TAc Lancet. 

" As a full, systematic, and thoroughly practical guide for the student and 
physician, it is not excelled by any similar treatise hi any language." Appldons* 
Journal. 

" The author is an accomplished pathologist and practical physician ; he is not 
only capable of appreciating the new discoveries, which during the last ten years 
have been unusually numerous and important in scientific and practical medicine^ 
but, by his clinical experience, he can put these new views to a practical test, and 
give judgment regarding them." Edinburgh Medical Journal. 

" From its general excellence, we are disposed to think that it will soon take 
its place among the recognized text-books. "American Quarterly Journal of 
Medical Sciences. 

" The first inquiry in this country regarding a German book generally is, ' Is 
it a work of practical value ? " Without stopping to consider the justness of the 
American idea of the ' practical,' we can unhesitatingly answer, ' It is ! ' " New 
York Medical Journal. 

" The author has the power of sifting the tares from the wheat a matter of 
the greatest importance in a text-book for students." British Medical Journal. 

" Whatever exalted opinion our countrymen may have of the author's talents 
of observation and his practical good sense, his text-book will not disappoint 
them, while those who are so unfortunate as to know him only by name, have in 
store a rich treat." New York Medical Record 



D. Applet on & (70. 's Medical Publications. 

NEUMANN. 
Hand-Book of Skin Diseases. 

By DR. ISIDOR NEUMANN, 
Lecturer on Skin Diseases in the Koyal University of Vienna. 

Translated from advanced sheets of the second edition, furnished by the 
Author ; with Notes, 

By LUCIUS D. BULKLEY, A. M., M. D., 

Surgeon to the New York Dispensary, Department of Venereal and Skin Diseases ; Assist- 
ant to the Skin Clinic of the College of Physicians and Surgeons, New York; Mem- 
ber of the New York Dermatological Society, etc., etc. 

1 vol., 8vo. About 450 pages and 66 Woodcuts. Cloth, $4.00. 

SPECIMEN OP ILLUSTRATIONS. 




Section of skin from a bald head. 

Prof. Neumann ranks second only to Hebra, whose assistant he was for many years, 
and his work may be considered as a fair exponent of the German practice of Dermatolo- 
gy. The book is abundantly illustrated with plates of the histology and pathology of the 
skin. The translator has endeavored, by means of notes from French, English, and Ameri- 
can sources, to make the work valuable to the student as well as to the practitioner. 

" It is a work which I shall heartily recommend to my class of students at the Univer- 
sity of Pennsylvania, and one which I feel sure will do much toward enlightening the pro- 
fession on this subject." Louis A. Duhring. 

" I know it to be a good book, and I am sure that it is well translated ; and it is inter- 
esting to find it illustrated by references to th,e views of co-laborers in the same field/' 
Erasmus Wilson. 

" So complete as to render it a most useful book of reference." T. McCatt Anderson. 

"There certainly is no work extant which deals so thoroughly with the Pathological 
Anatomy of the Skin as does this hand-book."^. T. Medical Record. 

"The original notes by Dr. Bulkley are very practical, and are an important adjunct to 
the text. ... I anticipate for it a wide circulation." Silas Durkee, Boston. 

"I have already twice expressed my favorable opinion of the book in print, and am 
glad that it is given to the public at last." James C. White, Boston. 

"More than two years ago we noticed Dr. Neumann's admirable work in its original 
shape ; and we are therefore absolved from the necessity of saying more than to repeat 
our strong recommendation of it to English readers." Practitioner. 



UNIVERSITY OF CALIFORNIA 
MEDICAL SCHOOL LIBRARY 

THIS BOOK IS DUE ON THE LAST DATE 
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per volume after the third day overdue, increasing to 
$1.00 per volume after the sixth day. Books not in de- 
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3m-2,'37 




. LIBRARY